Interiorscape
Integrated Pest Management



North Carolina
Cooperative Extension Service
College of Agriculture and Life Sciences
North Carolina State University

CHAPTER FOUR
INSECT MANAGEMENT IN THE
INTERIORSCAPE ENVIRONMENT

Commercial indoor landscape accounts are perhaps the most difficult areas in which to attempt pest control. Interior plantscapes extend from public conservatories to extensive plantings in homes, hotels, office buildings, restaurants, shopping malls, hospitals, schools, and other environmentally sensitive areas. The use of insecticides in many of these areas is often greatly restricted because of the sensitivity of the surroundings. In addition, few chemicals are cleared for ornamental plant use in public areas, and public prejudice against pesticide odors can prevent application of pesticides in many situations.

An amazing variety of insects feed on flowering and foliage plants. The routine use of insecticides usually eliminates predaceous insects and mites. However, pests remaining after treatment sometimes tolerate commonly used insecticides. To stay in business, most commercial flower and foliage plant growers must become fairly sophisticated in using various types of pest management practices, insecticide formulations, application equipment, and in rotating insecticides from one chemical group to another.

COMPONENTS OF INTEGRATED
PEST MANAGEMENT

The first line of defense against ornamental plant pests is sanitation and quarantine. Taking steps to prevent pest problems is well worth the effort. Inspect plants thoroughly and only place insect-free plants into an indoor landscape. If possible, when insect infestations are first found, isolate infested plants to prevent spread of the infestation.

Monitoring

Constant vigilance for insects, mites, and diseases is required for effective pest management. An employee or certain employees should be assigned the responsibility of scouting for insects and other pests on a regular basis (perhaps weekly during the winter and twice weekly during the summer). Written records of where various pests are found should be kept. Pests can be monitored by using yellow and blue sticky cards, by using yellow pan traps, and by examining the foliage, flowers, and occasionally the roots.

For proper management, it is important to be able to recognize the various kinds of pests in their various stages of development.

Probably the most frequently misidentified pests are shore flies and darkwinged fungus gnats. Shore flies are of little economic consequence in the greenhouse but are very resistant to pesticides. Thus a grower can waste effort and pesticides trying to chemically control shore flies rather than trying to control algae the shore flies are breeding in. Another example of misidentification is the assumption that parasitized green peach aphids are some sort of new "tan" aphid. Parasitized aphids adhere to the plant fairly tightly, so in spite of repeated applications, these "tan" aphids seem to be impossible to kill.

Biological Control

Interest in biological control in indoor landscapes has expanded in recent years because of restrictions placed on interior plantscape pesticide applications, pesticide costs, poor control with pesticide products, phytotoxicity, and potential human health hazards. To be successful at managing pest problems with biological control agents requires a knowledge of the biology of the pest species, the biological control agent(s), and a great deal of time and commitment. Biological control systems do not look after themselves.

Pesticides

Thorough, timely applications of properly labeled pesticides are another important aspect of an integrated pest control program. Rotating infested plants back into a greenhouse where they can be treated thoroughly and revived in vigor before being returned to the indoor landscape is a sound practice but is often not practical. Treat commercial landscape areas at night, on weekends, or when a minimum number of people are present. The public should not be allowed in the vicinity of treated plants until the pesticide residue on the foliage has dried completely.

Record Keeping

A written log should be kept of pest type, locality, abundance, and all pesticides applied. Such records can be of long-term benefit as many pests tend to appear at about the same time each year. However, the short-term benefits of written records may be greater. Knowing what pests survive a pesticide application alerts the grower to the possibility of poor timing, poor application, or pesticide resistance in the pest population. A change in strategy, application technology, or type of pesticide can be made before the crops are significantly damaged.

APHIDS

KEY TO APHIDS MOST COMMONLY FOUND IN GREENHOUSES

1. CHRYSANTHEMUM APHID- Aphid dark mahogany brown; found exclusively on chrysanthemum.

1.' Aphid pale yellow, green, pink, or red; may be found on chrysanthemum but occur on other plants as well.

2. GREEN PEACH APHID- Cornicles long, slender, and pale in color but sometimes dark at the tip; body 2.0 millimeters long.

2.' MELON OR COTTON APHID- Cornicles shorter and uniformly dark; body 1 to 1.8 millimeters long.

CHRYSANTHEMUM APHID

SCIENTIFIC NAME:  Macrosiphoniella sanborni(Gillette)
ORDER:  HOMOPTERA
FAMILY:  Aphididae


Adult

Older Nymph

DESCRIPTION

Adult: The winged adults are about 2 to 2.5 millimeters long; soft bodied; and dark, shining mahogany brown. Due to their dark color they were once called "blackflies." Wingless adults are only 1.5 millimeters long. Small, black, sturdy cornicles are found on the end of the body.

Nymph: Nymphs resemble smaller versions of the adult aphids (0.6 to 1 millimeters). Nymphs have a dull, brick-red bodies with relatively long legs and antennae. The cornicles are short and dark. The outer two-thirds of the legs and antennae are gray (young nymphs) to dark gray. Older nymphs have proportionally longer cornicles. Those destined to be winged adults have wing buds in the later instars.

BIOLOGY

Host Plants: Chrysanthemum is the only known host for this aphid in North America, but it has been reported on a few related plants in Asia.

Damage: The chrysanthemum aphid feeds by piercing the plant surface with its threadlike mouthparts to suck out plant juices. They gather about the terminal buds and feed on the new growth. This feeding causes distorted growth and the leaves may be covered by the feeding aphids' honeydew and cast skins. Sooty mold may grow on the honeydew giving the leaves and stems a black appearance. Chrysanthemum aphids are able to transmit chrysanthemum vein mottle virus and chrysanthemum virus B.

Life Cycle: Only female chrysanthemum aphids are known. They reproduce by giving live birth to more females, without mating. Chrysanthemum aphids overwinter in greenhouses where they feed throughout the winter. During the warmer months they leave the greenhouses in search of new plants. They also may be moved about as plants are shipped or sold. When the winged female stage infests new plants, it usually starts feeding and producing live nymphs. Each female can produce four to eight young aphids per day.

Within about a week the new nymphs mature into wingless females which begin to bear young of their own. One aphid on a plant in a short time may build the population up to hundreds of individuals . As the plant becomes crowded, more and more of the offspring develop into winged females which in turn migrate to other plants to begin new infestations.

MANAGEMENT STRATEGIES

Infested plants in the greenhouse should be sprayed thoroughly when aphids are first noticed. On outdoor plantings, natural enemies may control minor infestations. For specific chemical controls, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of pests on ornamental plants.

GREEN PEACH APHID

SCIENTIFIC NAME: Myzus persicae (Sulzer);
ORDER:  HOMOPTERA 
FAMILY:  Aphididae

DESCRIPTION

Adult: The small adult green peach aphid is light to dark green or pink, with red eyes. Three dark lines run down its back. Wings may or may not be present. The tobacco aphid is similar and can be either red or green.

Egg: Found only in the northern United States, the egg is black and shiny for the green peach aphid. The tobacco aphid has not been found to have an egg stage.

Nymph: The wingless nymph resembles the larger adult.

BIOLOGY

Host Plants: Green peach aphids have been collected from over 100 plants, including a wide variety of vegetable and ornamental crops. Spinach, potatoes, and peaches (the host on which eggs are laid) seem to be especially favored hosts. Tobacco aphids will be pests primarily on tobacco and closely related plants such as flowering tobacco and Nicotiana. It is probably not a major pest, but will feed on pepper and eggplant as well as cole crops such as turnips, kale, and collards.

Damage: Aphids suck plant sap and contaminate the host with honeydew and cast skins. Some hospitals refuse to allow cut flowers in patients' rooms because of the mess by aphids. They are also the vectors of a number of plant viruses including tobacco, tomato, lettuce, dahlia, canna, and bee mosaics as well as tuber spindle, rugose mosaic, and leaf roll diseases of potato.

Life Cycle: In the northern United States, green peach aphids overwinter as eggs, but in the Southeast, no eggs are laid. Instead, female aphids give birth to young females during the growing season. The reproductive capacity of green peach aphids has been described as "fantastic." High reproductive rates- and resistance to pesticides make the green peach aphid a formidable pest in the greenhouse. Up to 30 generations per year may take place in this pest's southernmost range.

The tobacco aphid probably overwinters on weed hosts or on cole crops that remain alive through the winter. Tobacco aphids are not known to have an egg stage, and they reproduce by giving birth to live young female aphids without mating. Their young are able to produce young as well without mating. If the plant becomes too crowded or if it becomes late in the season and the aphids need to find a winter host, the aphids give birth to young that will grow up to have wings and can move to other plants. Differences on reproductive rates exist between the red and green forms of the tobacco aphids. The red form is able to reproduce much faster during extremely hot weather than the green form.

On chrysanthemums, green peach aphids feed on all parts of the plant (melon aphids feed only on the buds and leaves, and chrysanthemum aphids feed only on the stems and leaves). Green peach aphids will not become established in the presence of the other two aphids unless pesticides are applied. In that case, green peach aphids outlive both melon aphids and chrysanthemum aphids.

MANAGEMENT STRATEGIES

Because green peach aphids overwinter on weed hosts, infestations can occur in the greenhouse any time of year. Green peach aphids readily infest bedding plants and can be introduced into greenhouses whenever bedding plants are brought in from another grower. Although damage per aphid is often not serious, these aphids reproduce so rapidly that serious harm can be done in a short time.

Biological Control: Ladybugs, lacewings, syrphid flies, damsel bugs, wasps, and parasitic fungi tend to regulate green peach aphid populations outdoors.

Pesticides: These aphids' resistance to pesticides calls -for thorough applications whenever a new infestation is found. Tobacco aphids can be controlled in the same manner as green peach aphids. For specific chemical controls, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

MELON OR COTTON APHID

SCIENTIFIC NAME: Aphis gossypii Glover
ORDER:  HOMOPTERA
FAMILY:  Aphididae

Winged Adult


Winged Adult


Wingless Adult


Nymph

DESCRIPTION

Adult: This is a small aphid, smaller than most other aphids. The winged adults are about 1.25 millimeters long, soft bodied, and yellow to dark green with a black head and thorax. The wings are held rooflike over the abdomen at rest. Wingless adults tend to be 1.0 to 1.5 millimeters long, uniform in color, and yellow to dark green. The antennae and cornicles are shorter than those of winged adults. Cornicles are small, tail-pipe-like structures on the end of the body. Pale individuals tend to be smaller and to have fewer antennal segments than dark individuals.

Nymphs: Nymphs resemble adult aphids except for size (about 0.5 to 1.0 millimeter long). Those destined to be winged adults have wing buds in the later instars.

BIOLOGY

Host Plants: Melons and other cucurbits, okra, hops, strawberries, beans, spinach, tomatoes, clover, asparagus, citrus, catalpa, violet, hydrangea, begonia,ground ivy, and weeds are some melon aphid hosts. They have been discovered feeding on plants in 25 plant families. The melon aphid is an important pest of cotton and is also called the cotton aphid.

Damage: The melon aphid feeds by piercing the plant surface with its threadlike mouthparts to suck out plant juices. This feeding causes distorted growth, decreased yield, reduced quality of yield, and prematurely ripened fruit. The fruit may be covered by the feeding aphids' honeydew and by cast skins.

The melon aphid transmits several important plant viruses including cucumber mosaic, onion yellow dwarf, citrus quick decline, lily symptomless diseases, and lily rosette.

Life Cycle: The melon aphid is an important pest of both agricultural and ornamental plants. Being practically omnipresent, it feeds upon many host plants. The melon aphid spends the winter on weed hosts and on cold-tolerant plants probably both as nymphs and adult females in the south. During warm periods of winter they start feeding until cold weather inactivates them again. In the spring the adult females move to new hosts and start feeding and rapidly reproducing. In northern climates the aphid overwinters in the egg stage. Indoors and in greenhouses the aphids feed and reproduce throughout the winter. Melon aphids commonly start out on one plant and spread out from that point. On woody ornamentals such as gardenias, feeding is confined to new growth in the spring.

For the melon aphid there are two kinds of hosts, primary and secondary. In late fall, aphids feed upon primary plants mate and lay overwintering eggs. Melon aphids feeding on secondary plants always give birth to live young. In spring, winged forms usually infest new plants, both primary and secondary, and the females produce live nymphs. Within about a week the new nymphs mature into wingless females that begin to bear young of their own. As the plant becomes crowded, more and more of the offspring develop into winged females which in turn migrate to other plants to begin new infestations. Wingless forms usually predominate in low aphid populations.

MANAGEMENT STRATEGIES

Biological Control: Natural enemies may control minor infestations on outdoor ornamentals. Syrphid fly maggots and ladybird beetles and their larvae feed upon melon aphids. Braconid wasps parasitize the aphids, and ants feed on the honeydew excreted by feeding aphids.

Pesticides: Because the winged forms are 2 to 3.7 times more resistant to organophosphate pesticides than are wingless forms, infested plants in the greenhouse should be sprayed thoroughly when aphids are first noticed. For specific chemical controls, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

FLIES

KEY TO MOST COMMON FLY PESTS FOUND ON FLOWERS AND FOLIAGE PLANTS

1. Narcissus bulb fly: Larger flies, 10 to 12 millimeters long; dense covering of long hairs that gives a furry look, resembling that of bees.

1.' Smaller flies, 6 millimeters long or shorter; hairs scattered or very short, flies not bee-like.................... 2

2. Lesser bulb fly. Flies about the size of a housefly, 5 to 6 millimeters long; body shiny under a dense covering of short hairs.

2.' Flies smaller, 3 millimeters long or less; body either dull colored or with scattered long hairs .................3

3. Darkwinged fungus gnats: Antennae elongate, as long as head and thorax; flies dull black with uniformly dark-colored wings.

3.' Antennae no longer than head; pattern usually present on body or wings .............................................. 4

4. Liriomyza spp: Flies shiny black and yellow; wings clear.

4.' Shore flies. Flies dull; some species have patterned body or wings.

--------------

KEY TO MOST COMMON MAGGOTS FOUND ON FLOWERS AND FOLIAGE PLANTS

1. Darkwinged fungus gnats: Larva with shiny black head capsule; body slender, white, smooth; found in decaying roots or stems or soil around them, rarely even on terminals;mostly in greenhouses.

1.' Without head capsule, with a pair of downward curving mouth hooks; body a typical maggot, wider in middle and tapering to one or both ends, may have roughened skin or fleshy filaments protruding from body...................2

2. Liriomyza spp.: Tiny yellow maggots, smooth; mining in leaves of plants.

2.'Not yellow and not leafminers..................................3

3. Larvae found in roots, rhizomes or bulbs ......................4

3.' Shore flies: Larvae found among algae or on wet surfaces, in hydroponic operations, filters, wet benches, etc.

4. Narcissus bulb fly. Mature larva large, more than 10 millimeters long; with only 1 pair of very short fleshy filaments under the spiracular tube at end of body; spiracular tube about as long as wide.

4.' Lesser bulb fly. Mature larva small, less than 10 millimeters long; with 3 pairs of fleshy filaments around the spiracular tube; spiracular tube about twice as long as wide.

FUNGUS GNATS

SCIENTIFIC NAME:  Lycoriella spp. and Bradysia spp.
ORDER:  DIPTERA
FAMILY:  Sciaridae

Adult



Larva



Pupa

DESCRIPTION

Adult: The flies are slender with comparatively long legs and antennae. They are grayish-black and about 2.5 millimeters long.

Egg: The yellowish-white tiny eggs are 0.2 millimeter long and 0.1 millimeter wide.

Larva: Darkwinged fungus gnat maggots have shiny black head capsules and white bodies. The last body segment is lobed and helps push the insect along. Mature larvae are about 5.5 millimeters long.

Pupa: Initially white, pupae become dark shortly before the adult emerges.

BIOLOGY

Host Plants: Darkwinged fungus gnat maggots feed on the roots of alfalfa, carnations, clover, corn, cucumbers, Easter lilies, geraniums, lettuce, nasturtium, peppers, rape, poinsettias, potatoes, soybeans, wheat, and organic matter.

Damage: Damage first becomes apparent when plants lose their healthy appearance and wilt. Darkwinged fungus gnat adults are usually noticed before injury caused by the maggots is apparent.

Life Cycle: Darkwinged fungus gnat maggots have only recently been recognized as important pests in greenhouses and mushroom cellars. They are also pests of house plants. Several of these flies are of economic concern. Generally, darkwinged fungus gnats are most abundant in greenhouses in the winter and spring. Adults and larvae inhabit moist, shady areas. Adults live about 1week, during which time each female deposits 100 to 150 eggs. They are laid in strings of 3 to 40 in the top of the soil, usually near stems of plants. They hatch within 4 days in the greenhouse. There is a tendency for the progeny of each female to be all one sex.

The larvae begin feeding on the root hairs and roots usually in the upper centimeter of medium, working their way up the plant and into the stem; however, they also feed on any organic matter in the soil. Being somewhat gregarious, the larvae often form clusters in the soil. They mature in about 14 days, after which they construct a pupal case, made of silk and debris, in the soil. The pupal stage lasts about 3.5 days. Adults are weak fliers, but they run rapidly on the soil surface or may remain motionless.

MANAGEMENT STRATEGIES

Cultural Controls: Clean cultural practices and lack of excessive watering usually will prevent fungus gnat infestations. Since fungus gnats prefer potting mixes containing peat moss and abundant moisture, consider using bark mixes and avoid overwatering ornamental plants. Decoy pots of sprouting grain are attractive to females, that lay eggs in these pots. Afterwards, the pots should be submerged in boiling water or the contents destroyed in some manner every 2 weeks to destroy the eggs and maggots.

Biological Control: Fungus gnats have few efficient natural enemies. The predaceous nematode, Steinernema bibionis, has reduced fungus gnats in mushroom houses 85 percent when applied at a rate of 600 per square meter . Another nematode, Steinernema carpocapsae---, is now on the market for fungus gnat control in greenhouses.

Pesticides: Some species of fungus gnats in mushroom houses have developed up to 47-fold resistance to pyrethroid insecticides. For chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

SHORE FLIES

SCIENTIFIC NAME:   Scatella stagnalis (Fallen) and perhaps other spp.
ORDER:   DIPTERA
FAMILY:  Ephydridae


Adult


Larva


Egg

DESCRIPTION

Adult: Shore flies in the genus Scatella are small (2 millimeters), black flies with reddish eyes and gray wings with clear spots. Shore flies resemble eye gnats, fruit flies, or vinegar flies in general shape. Shore flies are sometimes confused with darkwinged fungus gnats which are about the same size and color. (Darkwinged fungus gnats are shaped more like miniature mosquitoes and have relatively long legs and antennae.)

Egg: Shore fly eggs are about 0.42 long and 0.2 millimeter wide. They are fairly rounded at both ends although there are small lobes on one end. The surface of the egg is covered with minute, faint polygons. The eggs remain white throughout the development of the embryo.

Larva: The tiny first stage maggots have two spiracles only at the rear. The next two larval stages have two spiracles on the rear and a spiracle on either side near the head. The mature maggot is about 2.6 millimeters long and 0.9 millimeter wide and 0.5 millimeter high. The hind spiracles are black and are located at the end of small but conspicuous tubes. The anterior spiracles each resemble the fingers of a slightly inflated rubber glove but these spiracles are microscopic and inconspicuous.

Puparium: The puparia of Scatella shore flies are brown to dark brown, curved, and tapered on both ends. The puparia are about 2.6 millimeters long and 0.9 millimeter wide. At the hind end, the spiracles resemble stiff antennae. On the front, the anterior spiracles stick out sideways like microscopic horns. The puparia are curved toward the top side of the developing fly.

BIOLOGY

Host Plants: Adult and immature shore flies feed on microscopic algae, dinoflagellates, bacteria, cyanobacteria, and other unicellular forms.

Damage: Neither adult nor immature shore flies feed upon ornamental plants. The damage caused by shore flies consists primarily in the excrement ("fly specks") left on the foliage of bedding plants and other ornamentals.

Because shore flies are often confused with darkwinged fungus gnats, control efforts are often wasted (darkwinged fungus gnats may be harmful to plants but are relatively easy to control; shore flies are harmless but are very difficult to control with insecticides). Sometimes shore flies become so abundant in greenhouses that the sheer numbers of flies becomes a deterrent to customers browsing or even employees working.

Life Cycle: Scatella shore flies are commonly found in greenhouses where they breed in algae growing on the potting mix, pots, benches and floors.

Females scatter eggs right on the surface of the potting mix. The eggs hatch in 2 to 3 days. The larvae are found within the crust of algae and very top layer of potting mix. The maggots feed on bacteria and yeasts as well as diatoms and flagellates growing on the surface of the potting mix.

The larvae mature in 3 to 6 days and pupate inside the skin of the last larval stage (this kind of pupa is called a puparium). The last larval skin affords the relatively tender and completely helpless pupa protection from environmental hazards (including insecticides). Some of the puparia are found on top of the potting mix or are very close to the surface. A new generation of adult flies emerges 4 to 5 days later. The adults crawl about on the surface of the potting mix, on the plants or they fly about the pots and plants. The flies move and fly rapidly but generally stay close to their breeding sites. The adults feed primarily on diatoms and flagellates on the surface of the potting mix or mats.

MANAGEMENT STRATEGIES

Cultural Controls: Cultural methods of shore fly management include avoiding excessive use of water during irrigation, using the minimal optimum levels of fertilizers for adequate plant growth (and lower levels of excess fertilizers that encourage algal blooms), and a drier greenhouse environment. Algae on mats, benches, the walls or other structural members, and the soil beneath benches should be eliminated by using an approved algicide. Because shore fly maggots can also develop on rotting vegetable matter, general greenhouse sanitation should also help suppress shore fly numbers.

Pesticides: Perhaps because of the high biological activity of the surface of the potting mix, the protection afforded the pupa by the last larval skin, and the water repellent property of the adults, insecticides do not seem to readily suppress shore flies in greenhouses. Consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

INTRODUCTION TO MEALYBUGS

One of the more common groups of scale insects attacking ornamental plants are called mealybugs. There are about 275 species of mealybugs known to occur in the continental United States. Mealybugs are prevalent pests in greenhouses and interior plantscapes such as shopping malls, conservatories, hotels, and office buildings. Mealybugs cost growers and retailers millions of dollars per year in control costs and crop damage or loss. Damage is caused by mealybugs feeding on host tissues and injecting toxins or plant pathogens into host plants. In addition, mealybugs secrete a waste product, honeydew, which is a syrupy, sugary liquid that falls on the leaves, coating them with a shiny, sticky film. Honeydew serves as a medium for the growth of sooty mold fungus that reduces the plant's photosynthetic abilities and ruins the plant's appearance. Feeding by mealybugs can cause premature leaf drop, dieback, and may even kill plants if left unchecked.

Mealybugs are one of the more active groups of scale insects as most of them retain well-developed legs and remain mobile throughout their life. However, they generally move little once a suitable feeding site is found.

They are small insects (1 to 4 millimeters long) and the body is usually covered with a white cottony or mealy wax secretion. This makes them appear like small spots of cotton on the plant, particularly when the female is laying eggs and producing an ovisac to cover and protect the eggs. Mealybugs generally have an oval body outline. Many of them produce marginal filaments of wax that may be wedge-shaped or spine-like, but others lack marginal filaments entirely. As immatures, male and female mealybugs look alike, but as adults they are quite different. The adult male looks more like a small two-winged fly.

The life history of mealybugs varies depending on the species. Basically female mealybugs go through four developmental stages or instars and as adults may lay up to 600 eggs, usually in a cottony-like ovisac beneath her body. The eggs hatch in 6 to 14 days and the first instars or "crawlers", as they are commonly called, disperse to suitable feeding sites on new plant parts or hosts. They can survive only about a day without feeding, and once they insert their stylets to feed they generally remain anchored permanently. The crawler stage is the most fragile and easily controlled stage in a mealybug's life history. Some mealybugs, like the longtailed mealybug, do not lay eggs, but bear their young as active crawlers. Male mealybugs go through five instars and feed only in the first two instars.

Adult males have no functional mouthparts, live only a day or two, and exist solely to fertilize the females.

Outdoors most mealybugs go through one or two synchronized generations and overwinter as second instars. Indoors, there may be a continuous overlapping of generations and all stages can be found on the host at a given time. The citrus mealybug may have as many as eight generations indoors. The overlapping of generations makes control difficult. One of the first methods of control is to purchase plants that are not infested with mealybugs. Commercial flower growers sometimes discard plants infested with mealybugs rather than try to rescue them with insecticidal treatments.

Common mealybugs occurring indoors include: the citrus mealybug, the longtailed mealybug, the Mexican mealybug, and Pritchard's ground mealybug. Citrus mealybug is by far the most common and widespread mealybug pest. It attacks nearly every flowering species grown in the greenhouse.

KEY TO THE MOST COMMON MEALYBUGS FOUND ON FLOWERS AND FOLIAGE PLANTS

1. Longtailed Mealybug. Adult females with long, white filaments at the rear; females apparently giving birth to live young.

1.' Adult females without long, white filament at the rear; females lay eggs in a dense, white fluffy ovisac .... 2

2. Female feeding on above ground portion of plant......................3

2.' Pritchard's Mealybug and other root mealybugs. Female never feeding on above ground portions of plant; white mealybug feeding on roots.

3. Citrus Mealybug. Body orangish or purplish and covered with white bloom; a darker line down the middle of the back; mealybug very damaging to the health of many plants.

3.' Mexican Mealybug. Body purplish and covered with white bloom; three rows of white tufts down the back; may occur in high numbers with little effect on the health of the plant.

CITRUS MEALYBUG

Scientific Name:  Planococcus citri(Risso)
ORDER:  HOMOPTERA
FAMILY:  Pseudococcidae
A. Adult Female
B. Egg Mass
C - G. Nymphs
H. Adult Male

DESCRIPTION

Adult: The female citrus mealybug is wingless and appears to have been rolled in flour (hence the name). It grows to 3 millimeters long and 1.5 millimeters wide. A fringe of small waxy filaments protrude from the periphery. The male is small, but with its wings and tail filaments, it appears to be 4.5 millimeters long.

Egg: The oblong, yellow eggs are enmeshed in a dense, fluffy, white ovisac.

Crawler: The tiny crawler is oval and yellow, with red eyes. The antennae are rather distinct.

Nymph: Female nymphs resemble the larger adult females. Male nymphs are narrower and often occur in a loose cocoon.

BIOLOGY

Host Plants: Citrus mealybugs have been collected from at least 27 host plant families. Many ornamental plants grown in greenhouses are susceptible to attack including begonia, coleus, amaryllis, cyclamen, and dahlia. Citrus mealybug has been collected on canna, narcissus, and tulip outdoors.

Damage: Citrus mealybugs damage hosts by sucking out plant sap, by excreting honeydew in which sooty mold can grow, and by causing distorted growth and premature leaf drop with their toxic saliva. They further disfigure plants by secreting cottony wax. Infested plants usually die unless the pest is controlled.

Life Cycle: The citrus mealybug has been recognized as a pest of citrus and ornamental plants in Europe since 1813 (where it is called the greenhouse mealybug) and in the United States since 1879. Because female citrus mealybugs have no wings, they must be transported to the proximity of the next host plant. They can, however, travel short distances by crawling. The immatures can be blown about. Males are small, winged insects. After mating, each female lays up to hundreds of eggs in a dense, fluffy secretion called the egg sac or ovisac. Within a few days, new mealybugs (crawlers) hatch and begin to squirm out of the ovisac. Light infestations are easily overlooked because the mealybugs tend to wedge into crevices on the host plant. As their numbers increase, mealybugs of all sizes can be seen crawling around or feeding on all exposed plant surfaces.

MANAGEMENT STRATEGIES

Control of citrus mealybugs is amazingly difficult. Some commercial flower growers merely discard infested plants rather than trying to rescue them from citrus mealybugs. Horticultural oils may damage amaryllis. For specific chemical controls, consult your local Cooperative Extension Service or North Carolina's pest management guidefor the control of ornamental plant pests.

LONGTAILED MEALYBUG

SCIENTIFIC NAME: Pseudococcus longispinus (Targioni-Tozzetti)
ORDER:  HOMOPTERA
FAMILY:  Pseudococcodae
A. Adult

B. Nymphs

DESCRIPTION

Adult Female: Up to 3 millimeters long, female longtailed mealybugs have 17 pairs of waxy filaments around the periphery. On mature specimens, the caudal (tail) filaments are as long as or longer than the yellowish to grayish body (unless the tail filaments have broken off). Overall length maybe 6 to 7 millimeters.

Egg: There is no external egg stage of the longtailed mealybug.

Nymphs: The nymph is similar to the larger adult female except that the filaments around the edges are shorter.

BIOLOGY

Host Plants: Longtailed mealybugs have been found on at least 26 plant families. Dracaena appears to be the favored host, but most flowering and ornamental foliage plants are susceptible.

Damage: Longtailed mealybugs feed by sucking out plant sap from leaves and stems. Honeydew and sooty mold further disfigure infested plants, which may eventually be killed. These pests also secrete a fluffy white wax which also detracts from the appearance of infested plants.

Life Cycle: Although longtailed mealybugs were first described in 1867, not much has been published on their biology. Females give birth to live young on a shallow pile of white waxy secretions. Because the females are wingless, they must be brought into proximity of a host plant before it can be infested.

MANAGEMENT STRATEGIES

Biological Control: A small wasp, Anagyrus nigricornis, parasitizes longtailed mealybugs, and a small, predaceous, brown lacewing insect feeds on them. Ants sometimes protect longtailed mealybugs from parasites and predators and feed upon the honeydew excreted by these mealybugs.

Pesticides: Longtailed mealybugs are sometimes difficult to control, even though there is no egg stage protected by a dense ovisac. If many plants are infested, they should be dipped or sprayed thoroughly with a pesticide mixture or the entire greenhouse treated with an aerosol. It is best to retreat two or more times at weekly intervals. Retreatment will control mealybugs that were missed by earlier control efforts. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

MEXICAN MEALYBUG

SCIENTIFIC NAME: Phenacoccus gossypii Townsend and Cockerell
ORDER:  HOMOPTERA
FAMILY:  Pseudococcidae
Adult female

DESCRIPTION

Adult: The female Mexican mealybug adult is 3 to 4 millimeters long, oval, grayish and covered with a thin waxy secretion. There are three parallel rows of small waxy tufts down the back. This insect is a short-tailed mealybug (the caudal filaments do not exceed 1/4 the body length). The lateral filaments are also short. Males are small gnat-like insects with only two wings. Adult Mexican mealybug males have four waxy, posterior filaments.

Eggs: The egg sac is white, dense, narrow, and longer than the female secreting it.

Nymphs: The nymphs are small and yellowish with white waxy secretions.

BIOLOGY

Host Plants: The Mexican mealybug is found commonly on numerous ornamental plants, a few of which are aralia, chrysanthemum, English ivy, geranium, Gynura, hollyhock, Ixia, lantana, and poinsettia. This insect is also a minor pest of lima beans in the warmer parts of the United States.

Damage: Wilting and stunting are common symptoms of Mexican mealybug attack. This insect can be as damaging as the citrus mealybug. The mealybugs and ovisacs also disfigure heavily infested plants.

Life Cycle: In the greenhouse, the Mexican mealybug may have seven complete generations in one year. The average time required from oviposition to the adult stage is 47 days. Each female deposits about 400 eggs. The eggs are enclosed in an elongate cottony mass called the ovisac that originates at the back of the female. The ovisac is about 6 millimeters long. The eggs hatch in 6 to 14 days. The life cycles of the male and female Mexican mealybugs differ. A female passes through three nymphal stages only. Male Mexican mealybugs pass through two nymphal stages and two resting stages (prepupal and pupal stages). Normally, these mealybugs are found above ground on the leaves, stems or flowers, but occasionally will be found feeding on the roots.

MANAGEMENT STRATEGIES

Pesticides: For chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

ROOT MEALYBUGS

SCIENTIFIC NAME: Ground Mealybug: Rhizoecus falcifer Kunckel d'Hercularis
                         Pritchard's Mealybug Rhizoecus pritchardi McKenzie
ORDER:  HOMOPTERA
FAMILY:   Pseudococcidae
A. Adults

E. Eggs

N. Nymph

P. Particle of perlite

DESCRIPTION

Adult Female: The ground mealybug is white and 2.4 to 3.9 millimeters long. It resembles a springtail, but moves much more slowly and cannot jump. The ground mealybug has slender waxy filaments that form a sort of netting over some individuals. The ground mealybug also secretes a small amount of wax, which can give the soil a somewhat bluish appearance when the mealybugs are abundant. Pritchard's mealybug is snow white and 1.6 to 2.1 millimeters long and oval. It has small- to non-existent eyes.

BIOLOGY

Host Plants: The ground mealybug feeds on the roots of anemone, chrysanthemum, gladiolus, iris, and numerous other flowers, shrubs, and ornamental grasses. Pritchard's mealybug has become a serious pest of African violet, although it also infests Achillea, Arctostaphylos, Geum, and Polygala.

Damage: At times the ground mealybug becomes abundant enough to damage its host. Pritchard's mealybug causes devitalization, foliage deterioration, and even death of its host plant.

Life Cycle: Little has been published on the life history of root mealybugs. When infested African violets are irrigated, Pritchard's mealybugs crawl out of the drainage holes and spread throughout the greenhouse. Eggs are laid in a loose ovisac in clusters of at least six eggs. All stages can be found on the roots and potting mix of African violets where they resemble slow moving, snowy white collembola.

MANAGEMENT STRATEGIES

Pesticides: Pesticides applied as dips, drenches, or granulars are more effective for root mealybug control than are foliar sprays. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

INTRODUCTION TO MITES

Although mites differ from insects in several ways, their damage to ornamental plants resembles that of thrips and lace bugs. Most mites have eight legs as adults (adult insects usually have six). Mites do not have wings (some adult insects have wings) but can be aerially dispersed by breezes and winds more or less like aerial plankton, particularly in hot, dry weather. It is thought the mouthparts (chelae) of mites evolved from legs with a prehensile joint, (the digitus mobilus) which allows the mite to chew with a vertical, scissors like action. In spider mites, broad mites, and cyclamen mites, the chelae have evolved into sharp mouthparts that mites use to pierce the surface of the plants they feed on in order to suck out the contents of the plant cells. Mites evidently inject saliva as they feed for one of the first symptoms of broad mite and cyclamen mite feeding is failure of the host plant to blossom. Infested plants then exhibit a variety of plant growth regulator symptoms including twisted and distorted growth, and shortened internodes and petioles.

KEY TO THE MOST COMMON MITES FOUND ON FLOWERS AND FOLIAGE PLANTS

1. Mites visible to the naked eye; infested plant may be discolored but usually not distorted by feeding...........2

1.' Mites not visible without at least a 10 X hand lens; infested plants usually cease blooming and have shortened internodes, distorted leaves and stems, and blasted buds...........3

2. Twospotted spider mite. Mites feeding on foliage and causing tiny chlorotic spots, mites sometimes accompanied by fine silk webbing.

2.' Bulb mites. Mites feeding primarily in the bulbs of Easter lilies.

3. Broad mite. Egg oval, about 0.08 millimeter long, covered with minute white bumps; female translucent brown and about 0.2 millimeter long, shaped like a fat football.

3.' Cyclamen mite. Egg oval, about 0.1 millimeter long, without minute bumps; female translucent brown, about 0.3 millimeter long, shaped like a skinny football.

BROAD MITES

SCIENTIFIC NAME: Polyhagotarsonemus latus (Banks)
ORDER:   PROSTIGMATA
FAMILY:  Tarsonemidae

Egg


Adult Female


Adult Male


Nymph

DESCRIPTION

Adult: Broad mites are almost microscopic (less than 0.2 millimeter long). They are translucent and colorless to pale brown. There are four pairs of legs; the last pair in the female ends in a long hair; the last pair on the male ends in a strong claw.

Egg: The egg is elliptical, translucent, colorless, about 0.08 millimeter long, and is covered by 29 to 37 whitish bumps.

Larva: The young broad mite has three pairs of legs and is whitish due to minute ridges on the skin. It is about 0.1 millimeter long.

BIOLOGY

Host Plants: Broad mites infest African violet, ageratum, azalea, begonia, dahlia, gerbera, gloxinia, ivy, jasmine, impatiens, lantana, marigold, peperomia, snapdragon, verbena, and zinnia.

Damage: Infested plants become unthrifty. Leaves curl downward and turn coppery or purplish. Internodes shorten and lateral buds break more than normal. This new growth may also be stunted or killed, which forces out additional shoots. Flowers are distorted and fail to open normally. Unless controlled, broad mites usually destroy the commercial value of infested ornamental corps. Broad mites damage flowers and foliage of begonia and cyclamen, and bronze the lower leaf surfaces. Broad mites are so small that they are virtually invisible on the host plant even with a good hand lens.

Also the mites tend to crowd into crevices and buds and feed on the growing tips. Their toxic saliva causes twisted, hardened and distorted growth in the terminal of the plant. The effects of their feeding may persist long after the mites have been eradicated.

Life Cycle: Female broad mites lay 30 to 76 eggs on the leaf surface over an 8- to 13-day oviposition period. Unmated females lay male eggs; mated females usually lay four female eggs for every male egg. The larvae hatch in 2 or 3 days and emerge from the egg shell to feed. Larvae are slow moving and do not disperse far. In 2 or 3 days, the larvae develop into a quiescent larval stage. Quiescent female larvae become attractive to the males which pick them up and carry them to the new foliage. Males and females are very active, but the males apparently account for much of the dispersal of a broad mite population in their frenzy to carry the quiescent female larvae to new leaves. When females emerge from the quiescent stage, males immediately mate with them. Males live 5 to 9 days; females live 8 to 13 days.

MANAGEMENT STRATEGIES

Cultural control: Broad mites are very sensitive to heat. Lowering infested plants into water held at 43 to 49°C for 15 minutes will destroy broad mites without damaging the plants.

Pesticides: Broad mites are susceptible to various miticides. However, they are more difficult to control in winter than in summer due to lower greenhouse temperatures. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

CYCLAMEN MITES

SCIENTIFIC NAME: Stenotarsonemus pallidus(Banks)
ORDER:   ACARINA
FAMILY:  Tarsonemidae


Female


Male


Egg


Larva

DESCRIPTION

Adult: These mites are tiny animals, less than 0.3 millimeter long. Colorless or brown tinted and waxy looking, they have four pairs of legs. The fourth pair of the female is slender with a long, hair extending from the tip. The fourth pair of legs of the males ends in a strong claw.

Egg: The elliptical egg is 0.1 millimeter long and smooth.

Larva: The young mites are about 0.2 millimeter long and are whitish and have three pairs of legs. The legs have microscopic claws and suction cups.

Quiescent Stage: This stage appears as an immobile, engorged larva.

BIOLOGY

Host Plants: African violets are most often damaged by cyclamen mites. They also have been found on ivy, snapdragon, chrysanthemum, larkspur, geranium, fuschia, begonia, petunia, daisy, and azalea.

Damage: Cyclamen mites cause tuberous begonia and cyclamen flowers to be discolored or to shrivel or wilt. Infested flowers may not open properly or may not open at all. The mites also cause puckering, crinkling, and curling of leaves; infested leaves become brittle. Infested cyclamen buds fail to open or the flowers are distorted.

Life Cycle: Cyclamen mites were first reported in the United States about 1900. It has since become famous as a harmful plant pest. Cyclamen mites seem to avoid the light; they occur in hidden areas on plants (buds and between the calyx and corolla and the stamens and ovaries of flowers). This mite also prefers high humidity. The eggs have delicate shells that can often be found collapsed among masses of unhatched eggs and mites. Deposited in moist, dark places and in small groups, the eggs require about 11 days to hatch. The mites molt only once.

New larvae have wrinkled skin that stretches as they grow. They are highly active for about one week, after which they enter a quiescent stage for a few days and then molt to the adult stage. Each day the female lays two or three eggs. Eggs are relatively large in comparison to the adults. Cyclamen mites often exist wherever old cyclamen corms are preserved in the greenhouse. If a suitable host is not present year-round, female mites may semi-hibernate in the soil until a host becomes available. Females are usually more abundant than males in the winter months, and they live longer than males.

MANAGEMENT STRATEGIES

Cultural Control: Immersing infested plants (pot and all) into water heated to 43° C for 15 minutes kills cyclamen mites without harming most plants.

Pesticides: If chemical control is desired, spray or dip the plant thoroughly with a miticide. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

TWOSPOTTED SPIDER MITE

SCIENTIFIC NAME: Tetranychus urticae Koch
ORDER:   PROSTIGMATA
FAMILY:  Tetranychidae

DESCRIPTION

Adult: The eight-legged adult can be pale green, greenish amber, or yellowish. Usually having two (sometimes four) black spots on top, the twospotted spider mite is about 0.4 millimeters long.

Egg: The spherical egg ranges from transparent and colorless to opaque straw yellow.

Larva: The six-legged larva is colorless, pale green, or yellow.

Nymph: Similar to the adult except in size, the nymph has eight legs and is pale green to brownish green. Large black spots may develop on each side.

BIOLOGY

Host Plants: Twospotted spider mites have been reported on over 300 host plants, that include over 100 cultivated species. Violets, chickweed, pokeweed, wild mustard, henbit, vetch, and blackberry are common foci from which infestations develop on nearby crops.

Damage: Twospotted spider mites pierce the epidermis of the host plant leaf with their sharp, slender mouthparts. When they extract the sap, the mesophyll tissue of the leaf collapses in the area of the puncture. Soon a chlorotic spot forms at each feeding site. After a heavy attack, an entire plant may become yellowed, bronzed, or killed completely. The mites may completely web over entire plants.

Life Cycle: Twospotted spider mites are important pests on more crops than any other arthropod in the Southeast. Though insects and mites are in a group called the Arthropoda (meaning jointed foot) because jointed legs are common to both, spider mites are not actually insects. They are more closely related to spiders, and they derive their name from the thin web which some species spin.

In North Carolina, twospotted spider mites overwinter as adults in the soil or on weed hosts such as violets, henbit, and hollyhocks. In mild winter weather, twospotted spider mites continue to feed and lay eggs, although development in the winter is much slower than in the summer. From the eggs hatch six-legged larvae. They develop into eight-legged nymphs which pass through two nymphal stages. After each larval and nymphal stage, there is a resting stage. The adults mate soon after emerging from the last resting stage, and in warm weather the females soon lay eggs. Each female may lay over 100 eggs in her life and up to 19 eggs per day. Development is rapid in hot, dry weather. Each generation may take as many as 20 or as few as 5 days to mature.

They often damage one species of plant quite heavily and then disperse to other hosts. When a plant is heavily damaged, the mites migrate to the outer periphery of the plant. From here, even the gentlest of breezes can carry them a significant distance to attack new hosts.

MANAGEMENT STRATEGIES

Cultural Control: If spider mite infestations are detected early enough, a daily misting or spraying with water can be an effective control.

Pesticides: The use of foliar insecticides in hot, dry weather can induce spider mite outbreaks by killing the beneficial arthropods that would normally feed on the mites. In addition, a fungal pathogen attacks spider mites following short periods of cool, damp weather. Certain fungicides can eliminate this fungus and should be avoided for several weeks if plants are infested and such conditions occur.

The resting stages and eggs of the twospotted spider mite are more tolerant to pesticides than the motile forms. Consequently, a second application of pesticide may be necessary at 4- or 5-day intervals in hot weather (7 to 10 days in cool weather) to kill those mites that may have survived the first application. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

INTRODUCTION TO SCALE INSECTS

Scale insects are a diverse group of insects in the order HOMOPTERA. There are about 6,000 species of scale insects in 21 families worldwide. About 1,000 species occur in North America. The three most common families of scale insects are the armored scale, the soft scale, and the mealybugs. Most of the pest species belong to one of these three families.

Armored Scale Insects: Armored scales are the smallest of scale insects, ranging in size from 1 to 3 millimeters. The body of the scale insect is protected by a cover (the armor) made from wax secreted by the insect and cast skins (exuviae) of previous growth stages. One must remove the hardened wax cover to expose the body of the insect. The exposed body usually is yellow or orange, but may have a pink or red color to it. This cover also protects the eggs laid by the female. Armored scale insect covers vary from circular to elongate or oyster shell-shaped. Male and female covers may differ in size and shape for the same species. The cover of the female is generally largest. Boisduval scale and fern scale are common armored scale insects attacking flowers and foliage plants.

Most armored scale insects reproduce sexually. The eggs hatch beneath the protective scale cover and the first instars, commonly called "crawlers", migrate to the new growth to settle and feed. Armored scale females lose their legs at the first molt and are sessile for the rest of their lives. Females develop through three instars and males develop through five. Armored scales may overwinter as eggs, nymphs, or adult females. Adult males are usually present about two weeks in each generation. Some armored scales have four generations per year.

Soft Scale Insects: Soft scales differ from armored scales in that they do not secrete a waxy covering that is separate from the body. If wax is present, it adheres tightly to the body of the female and cannot be easily separated from it. Most soft scales produce a thin, glassy wax that does not obscure the color or form of the female soft scale. Soft scales are fairly large (2 to 6 millimeters long) and can be distinguished by their larger size, round or oval body outline, and convex or hemispherical profile. Soft scale females vary from flat to almost spherical. Often different host plants will alter the body form of a single species so much that taxonomists have described the different forms as separate species. If one turns the adult soft scale over, legs, antennae and thread-like mouthparts are readily visible with the aid of a microscope. Three common soft scales found in greenhouses and interior plantscapes are the brown soft scale, hemispherical scale, and tessellated scale.

Soft scales may reproduce sexually or parthenogenetically and every female may be capable of producing progeny without fertilization. Tremendous populations can develop during a single growing season. Most outdoor species have one generation per year. Females either lay eggs or give live birth, depending on the species. There are three instars in the females and five instars in the males. In warmer climates and in greenhouses, species with multiple generations may have all stages present simultaneously throughout the year.

KEY TO SCALE INSECTS

1. Body of insect protected with a wax or vanish-like covering that is not attached to the body of the insect; the insect can be seen by lifting off this covering. Armored scale insects.....2

1.' Body of insect oval in top view, bare or covered with a clear glassy-type wax that adheres to the insect's body; infested plants often sticky with honeydew excreted by the insect. Soft scale insects. ......3

2. Fern Scale. Scale covering of female brownish and oystershell shaped; male cover snow-white with three ridges down the back.

2.' Boisduval scale. Scale covering circular or oval, thin, flat, white to light yellow, semitransparent, and exuviae central or subcentral; male cover oblong oval, white, also with three ridges down the back.

3. Hemispherical scale. Mature individuals noticeably convex or hemispherical in side view, shiny brown in color; sometimes hundreds of eggs found under the body.

3.' Mature individuals flat or only slightly convex in side view; yellowish-green to black in color; no eggs found under body although a few crawlers may be present under the female ....4

4. Brown soft scale. Body yellowish-green to yellowish-brown in color; often mottled with brown spots.

4.' Tessellated scale. Body oval, opaque, reddish-brown, and 4 to 5 millimeters in length; the dorsal surface appears checkered or cellular in pattern when examined with a magnifying glass.

BOISDUVAL SCALE

SCIENTIFIC NAME: Diaspis boisduvali Signoret
ORDER:  HOMOPTERA
FAMILY:   Diaspididae

DESCRIPTION

Adult Female: Cover of the adult female boisduval scale is circular or oval, thin, flat, white to light yellow, semitransparent, and 1.2 to 2.25 millimeters in diameter. Exuviae central to subcentral in position.

Other Stages: The male cover is somewhat rectangular in shape, elongate, about 1 millimeter in length, and snow white with three ridges down the back.

Eggs: Boisduval scale eggs are oval and pale yellow to pale orange.

Nymphs: Newly settled nymphs are pale orange.

BIOLOGY

Host Plants: Cattleya and Cymbidium orchids are the most common hosts, but this scale insect thrives on the leaves and bark of other orchids, palms, banana, and cacti.

Damage: New growth is frequently attacked prior to opening, and leaves may be killed if the infestation is dense. Lighter infestations produce irregular chlorotic spots that mark feeding sites and spoil the appearance of the leaves.

Life Cycle: Under greenhouse conditions, boisduval scale can complete its life cycle in about 50 days. Females may produce up to 200 eggs in a lifetime.

Eggs hatch in 5 to 7 days and most of the crawlers settle to feed within 24 hours after hatching. The first stage lasts about 10 days, the second about 8 to 10 days for females and 15 for males. After mating, females retain their eggs for a short period, then oviposit. Because females produce eggs over a long period, generations overlap, and usually all stages can be found at any one time. Crawlers can settle anywhere on the leaf, but seem to prefer the midrib and major veins.

MANAGEMENT STRATEGIES

Try to purchase plants from a supplier who does not have a scale infestation.

Pesticides: When scales are encountered, horticultural oils give adequate control without excessive phytotoxicity. Two thorough treatments 2 weeks apart should give good control. Boisduval scale crawlers often establish themselves near the base of the plant and in leaf sheaths making control difficult. Also, both upper and lower leaf surfaces are attacked, so thorough coverage of any treatment is essential. For specific control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

BROWN SOFT SCALE

SCIENTIFIC NAME: Coccus hesperidium Linnaeus
ORDER: HOMOPTERA
FAMILY: Coccidae

Crawler

Mature Female

DESCRIPTION

Adult: Living adult female brown soft scales are pale yellowish green to yellowish brown, often mottled with brown spots. Older females are brown. The body is usually oval in outline, 2.5 to 4 millimeters in length and slightly convex in profile. The shape tends to vary according to position on the host plant. Males look like tiny two-winged wasps or flies and are rare.

Other Stages: Crawlers and young nymphs are yellow and almost flat in profile. Parasitized nymphs are dark brown to black and convex. Crawlers have well-developed legs and antennae and are quite active until settling. Older nymphs are sessile.

BIOLOGY

Host Plants: Brown soft scale has been reported feeding on hundreds of different plants. It can survive on most greenhouse plants, but seems to prefer perennials over annuals. Ferns are a favored host.

Damage: Brown soft scale is probably the most frequently encountered scale on plants indoors. Infestations of brown soft scale can become so heavy as to encrust the stems and petioles of their host plant. They also settle on leaves, usually along midribs and occasionally on the fruit. Large colonies remove large quantities of plant fluids and can cause wilting, but they seldom kill their host. Immatures and adults produce much honey dew that serves as a medium for the growth of sooty molds. These fungi inhibit photosynthesis and make infested plants unsightly. Obnoxious insects such as ants and wasps are also attracted to feed on the honeydew.

Life Cycle: Females are ovoviviparous and retain the eggs in the body until hatching. Brown soft scales are born as active crawlers but remain under the body of the female for a short time before emerging and selecting a feeding site to settle and complete their development. Females molt twice before reaching maturity. Males undergo four molts before emerging as winged adults, but are rarely seen. All stages are found throughout the year in warmer regions and in greenhouses. Brown soft scales can complete three to seven generations per year depending on temperature. It takes about 60 days to complete a generation.

MANAGEMENT STRATEGIES

Brown soft scales are surprisingly difficult to control even though there is an external egg stage and only a few very young nymphs are protected by the body of the mother.

Biological Control: Although reported as a pest species of many host plants in many countries, outdoors it may be suppressed by natural enemies in many areas. Scutellista cyanea Motschulsky is a common parasite and Metaphyous luteolus Timberlake controls brown soft scale in California.

Pesticides: For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

FERN SCALE

SCIENTIFIC NAME: Pinnaspis aspidistrae (Signoret)
ORDER:  HOMOPTERA
FAMILY: Diaspididae

DESCRIPTION

Adult: Female fern scale armor is oystershell or pear shaped, flat, light brown with the crawler cast skin a paler brown. Sometimes the second stage armor is also paler than the adult armor. They are 1.5 to 2.5 millimeters long. The male armor is white felted, three-ridged, and the crawler cast skin is beige to yellowish brown. Adult males are tiny, two-winged, gnat-like insects that are easily overlooked.

Egg: Eggs of armored scales are usually oval and about 0.2 millimeter long. They are laid in groups under the female armor.

Crawler: Fern scale crawlers are about 0.2 millimeter long, flat, and yellow with red eyes. The legs and antennae are well developed.

Nymph: Female second-stage nymphs secrete an oval, pale brown armor about 0.8 millimeter long. Male second stage nymphs secrete a white armor which has three long ridges. Mature male second stage nymphs are about 1 millimeter long.

BIOLOGY

Host Plant: Fern scales mainly infest true ferns (not asparagus ferns) and liriope. This pest has been recorded from numerous foliage plants, citrus, and other woody ornamental trees and shrubs in Florida.

Damage: Infested ferns are disfigured by the presence of male second stage armor which is conspicuous against the dark green foliage. Ferns in commercial production sometimes tolerate a tremendous scale population with little noticeable reduction in vigor or color. Feeding by female scales causes yellow spots on some fern varieties and on liriope. Males do not feed beyond the second stage of development.

Life Cycle: Little specific information is known about the biology of fern scales. Female scales lay their eggs under the armor. The female dies after the last egg is laid. Tiny crawlers hatch from the eggs and eventually emerge from under the mother's armor. The crawlers move about until they begin to feed by inserting their long, thread-like mouthparts into the leaf and sucking out nutrients. The insect molts into a second stage which begins to secrete a waxy material from under the rear of the first stage (crawler) cast skin. Eventually these insects molt into the adult stage. Female scales begin to secrete the adult armor at the rear of the second stage armor. Males emerge from their second stage armor as tiny, gnat-like insects that crawl or fly to female scales to mate. The armor remains fastened to the plant long after the scale insect leaves (male) or dies inside (female). When populations become dense, females tend to lay male eggs so that heavily infested plants become conspicuously spotted by second stage male armor.

MANAGEMENT STRATEGIES

Try to purchase plants from a supplier who does not have a fern scale infestation.

Pesticides: When fern scales are encountered, horticultural oils give adequate control without excessive phytotoxicity to ferns. Two thorough treatments 2 weeks apart should give good control. Ferns are notoriously sensitive to pesticides. Whenever treating ferns and other sensitive plants, treat at a time that the pesticide will be dry on the foliage before the plants are exposed to full sunlight. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

HEMISPHERICAL SCALE

SCIENTIFIC NAME: Saissetia coffeae (Walker)
ORDER:   HOMOPTERA
FAMILY: Coccidae

Top View

Side View

DESCRIPTION

Adult: Depending on the host plant, the adult scale may vary in size. The scale varies from 4.5 millimeters on Cycas to as small as 2.0 millimeters on Asparagus fern. Relatively hemispherical, brown, smooth, and shiny, the scale may resemble a miniature army helmet. Young females may have a pattern of ridges in the form of the letter "H" on the dorsal surface.

Egg: The oblong, pinkish beige eggs are about 0.7 millimeter long and are protected by the mother's body in a mass of hundreds.

Crawler: The flat, pinkish beige crawler is about 1.0 millimeter long with two red eye spots. The antennae and legs are short and spindly. There are two setae protruding from the rear.

Nymph: Nymphs are semitransparent, light yellow or pink, and flat (young) to humped (older). They are so closely attached to the host plant that the legs and antennae are concealed. Two pale lines start at the margin on each side and fade in intensity toward the middle. Nymphs and young adults may exhibit the characteristic "H" pattern of the black scale group.

BIOLOGY

Host Plants: The hemispherical scale insect has a wide range of hosts including bamboo, camellia, chrysanthemum, crape myrtle, croton, ferns, figs, gardenia, honeysuckle, lily, orchids, and zamia.

Damage: The secretion of honeydew and subsequent formation of sooty mold detracts from the beauty and commercial value of the plant. Feeding causes the plant to become stunted and lose its leaves.

Life Cycle: The hemispherical scale insect is a tropical insect that has become a common greenhouse pest. In warmer temperate areas, the scale can live outside. Unlike many other scales, the hemispherical scale secretes little wax. However, the scales do produce much honeydew which allows sooty mold to grow. Males are unknown and reproduction is by parthenogenesis. Each female may deposit up to 1000 eggs. After laying the eggs, the female dies and her body shrinks to form a cup or helmet over the eggs.

Development for the egg stage and the three nymphal instars requires at least 40 days and may take as long as 105 days. There may be several generations each year in the greenhouse, with all stages being present at any one time. The nymphs do not move much once they have begun to feed. The hemispherical scale insect has a low rate of parasitism indoors, and it often becomes a serious pest.

MANAGEMENT STRATEGIES

Biological Control: The most important parasite of hemispherical scale in the United States is Metaphycus helvolus Compere.

Pesticides: Hemispherical scale insects are relatively difficult to control because the eggs and young nymphs are protected by the body of the mother. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.

TESSELLATED SCALE

SCIENTIFIC NAME: Eucalymnatus tessellatus (Signoret)
ORDER:   HOMOPTERA
FAMILY: Coccidae

DESCRIPTION

Adult Female: Living adult females are flattened, reddish brown to dark brown, and 4-5 millimeters in length. The body is usually somewhat oval in outline, with the anterior end angulate and the posterior broadly rounded, but the shape may change due to position on the plant. When viewed under a hand lens or magnifying glass, the dorsal surface of the body has a checkered or cellular pattern, divided by a smooth longitudinal median ridge.

Crawlers: Tessellated scale crawlers are reddish brown, flat, elongate oval, and widest in the middle area of the body.

Nymphs: Settled nymphs are light golden in color, flat, oval, and adhering so closely to the leaf surfaces as to be nearly transparent. Males are unknown.

BIOLOGY

Host Plants: Tessellated scale occurs most commonly on palms and several species of Ficus, but it has been found on a wide variety of host plants.

Damage: Tesselated scale is primarily a leaf-infesting soft scale and a greenhouse pest. Heavy infestations weaken the plant but seldom kill it. Infestations are often of economic importance in commercial nurseries whenever pest management programs are neglected.

Life Cycle: One or two generations per year, and in greenhouses generations will overlap. Tessellated scale is parthenogenetic and ovoviviparous, giving birth to living young. Males are unknown.

MANAGEMENT STRATEGIES

Biological Control: The parasitic wasp, Metaphycus stanleyi Compere is a natural enemy of tessellated scale.

Pesticides: As with other scale insects, tessellated scale is best controlled in the immature stage. For specific chemical control recommendations, consult your local Cooperative Extension Service or North Carolina's pest management guide for the control of ornamental plant pests.