Contributors: J.R. Baker, Extension Entomology Specialist; D.M. Benson, Plant Pathology, Professor; L.F. Grand, Plant Pathology, Professor; R.K. Jones, Extension Plant Pathology Specialist; M.A. Powell, Extension Horticulture Specialist; D.L. Stephan, Extension Entomology Specialist; J. Scott, North Carolina Department of Agriculture; H. Singletary, North Carolina Department of Agriculture

ROSE INSECT PESTS

Pests vary in type and severity from area to area, however, many of them can be controlled effectively by keeping the rose garden clear of weeds, fallen rose leaves, and diseased or insect-infested canes.

Pesticide sprays or dusts should be applied only as needed. Three types of pesticides are used on roses: fungicides for diseases; miticides for spider mites; and insecticides for insects. These chemicals can be used as dusts or sprays. Ready-to-use dusts are available from pesticide dealers. Few sprays come ready to use on roses. It is usually necessary to prepare sprays by mixing wetable powders or emulsifiable concentrates with water. Pesticides should be selected by studying this section, the North Carolina Agricultural Chemicals Manual, and the pesticide container labels. Follow label directions for dilution and care in handling.

Because of their showy, fragrant flowers, roses are often used in North Carolina landscapes. However, the stems, leaves and flowers of roses are attacked by a large number of insects. Hybrid tea roses are particularly susceptible to thrips and spider mite injury. Blooms may be protected from insect attacks by covering them with cheesecloth or other coarsely woven cloth on a light framework.

INSECTS WITH PIERCING/SUCKING MOUTHPARTS

ROSE APHIDS
Photo courtesy of Dr. Jim Baker, North Carolina State University


Rose Aphids

Order:Hemiptera
Family:Aphididae
Scientific Name: Macrosiphum rosae

Description: The adult aphid is large (2.5 millimeters) and has long, dark legs and honey tubes. Its body is pink, purplish, or green. Adults may or may not have wings.

Nymphs resemble wingless adults except they are smaller. Both green and pink forms occur.

Biology: The rose aphid is found throughout the United States except in the arid Southwest. Rose aphids feed on rose and occasionally on pyracantha.

Rose aphids are often attracted to the new growth and flower buds of roses. Aphids suck out sap through their thread-like mouthparts, which results in the stunting of plants. The insects also secrete a sticky substance, called honeydew, which accumulates on foliage. Several species of aphids occur on stems, leaves, and buds of roses; however, rose aphids are unusual in that pink and green individuals occur as offspring of the same aphid.

The entire life cycle may be spent on one host plant. The female is parthenogenic and gives birth to live young throughout the growing season. In late fall, a generation of males and females is produced. After mating, females lay eggs on rose canes. The eggs overwinter. In spring new growth resumes, the eggs hatch and tiny nymphs begin to feed.

Control: Fly maggots, lady beetles, parasitic wasps, and green lacewing adults and larvae often help keep rose aphids under control. These biological control agents may keep rose aphid populations in check, except during cool weather. Control measures should be applied when aphids are first noticed. The North Carolina Agricultural Chemicals Manual should be consulted for current insecticide recommendations.

Leafhoppers

Order:Homoptera
Family: Cicadellidae
Scientific Name:

Description:

Biology: Leafhoppers are tiny, greenish-yellow jumping insects, frequently found on the underside of rose leaves. They feed by sucking plant juices through their thread-like mouthparts, causing a stippling of leaves resembling spider mite injury. Leafhoppers are seldom abundant enough to cause much damage, but their presence may be alarming. Leafhoppers may pop up on roses any time during the growing season because they infest many other ornamental and weed hosts and fly readily.

Control: Labeled insecticides should be applied to the underside of foliage. Consult the North Carolina Agricultural Chemicals Manual for current recommendations.

TWOSPOTTED SPIDER MITES
Photo courtesy of Dr. Jim Baker, North Carolina State University


Twospotted Spider Mites

Order:Prostigmata
Family:Tetranychidae
Scientific Name:Tetranychus urticae

Description: The eight-legged adult can be rusty green, greenish amber, or yellow. The overwintering female, however, is orange. The adult is approximately .375 millimeters long and usually has two black spots on the upper body.

Eggs are spherical and range in color from transparent and colorless to opaque straw yellow. Larva are six-legged and colorless to pale green or yellow in color.

Nymphs are similar to adults except smaller.

Biology: Twospotted spider mites are widely distributed in the United States.

These arthropods have been reported on over 180 host plants, including violets, chickweed, pokeweed, wild mustard, and blackberry.

Twospotted spider mites pierce host plant epidermal cells with their mouthparts and extract plant juices from the mesophyll tissue of rose leaves. Feeding injuries results in a tiny, chlorotic spot on the leaf. When many mites are feeding, the numerous tiny spots cause the whole leaf to appear dusty or off-color, bronzed, or yellowed. As the injury progresses the leaves turn brown, curl, and drop off. When the mites are abundant they spin a web over the leaf surface. Infested plants are unthrifty. If uncontrolled, spider mites may actually kill a rose bush.

The mites overwinter as adults on leaves of living weeds or perennial garden plants. In mild winter weather, these mites continue to feed and lay eggs, although development in the winter is much slower than in the summer. Six-legged larvae hatch from the eggs. 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 can lay up to 19 eggs per day. Development is most rapid during hot, dry weather. A single generation may require as many as 20 or as few as 5 days to reach adulthood and begin producing offspring. Mites are most abundant in hot weather.

Control: Living weeds may serve as alternate hosts and should be removed in early spring.

Insecticidal soap can provide good control of spider mite. Because spider mites go through resistant stages, it is usually necessary to treat two or three times for complete control. Wait 5 to 7 days between applications.

The resting stages and eggs of the twospotted spider mite are more tolerant to pesticides than motile forms.

Consult the North Carolina Agricultural Chemicals Manual for current recommendations.

Southern Red Mites

Order:Prostigmata
Family: Tetranychidae
Scientific Name: Oligonychus illicis

Description: The adult female is approximately 0.38 millimeters long and resembles a small spider. The abdomen is dark reddish or brown; the cephalothorax is pinkish or red; the female also has a pale midstripe. The male resembles the female but is smaller (0.30 millimeters) and is usually dark, lacking the pink or red color.

Eggs are brownish to reddish in color with a depressed central stipe or hair. Larvae are nearly white with a few reddish dots. Nymphs are similar to adult males in color.

Biology: The southern red mite was first reported on hollies at Batesburg, South Carolina in 1917. This spider mite is a common pest throughout the eastern United States and California and can be exceptionally destructive.

These mites prefer azaleas, camellias, and hollies. Plants in the Ericacae (heath) and Aquifoliaceae (holly) families also seem especially susceptible. They have also been found on clethra, cleyera, elaeagnus, eucalyptus, eugenia, grevillea, hibiscus, juniper, kalmia, oxalis, photinia, pyracantha, rhododendron, and viburnum.

Southern red mites feed on the lower leaf surfaces, causing mesophyll collapse. Infested leaves turn gray or brown and may fall from the shrub prematurely. However, if populations are high, they will feed on the upper surfaces as well.

These mites pass through a larval stage and a series of nymphal stages before they mature into adults. They reproduce rapidly in spring and fall and become almost inactive in winter and summer. They overwinter as eggs.

Control: Because southern red mites are most active in cool weather, predaceous insects and mites are not useful for biological controls.

Chemical treatments should be applied at the end of summer or winter for maximum effectiveness. Like the twospotted spider mites, southern red mites go through resistant stages as well and therefore, two or three treatments may be necessary for complete control.

Consult the North Carolina Agricultural Chemicals Manual for current recommendations.

Flower Thrips

Order: Thysanoptera
Family: Thripidae
Scientific Name: Frankliniella tritici

Description: Adult flower thrips are small (1.25 millimeters), hairy-winged insects that are yellowish brown to amber in color with an orange thorax. They have sucking-rasping mouthparts. Males are slightly smaller and lighter in color than females.

Eggs are cylindrical and slightly kidney shaped with a smooth, pale or yellow surface.

Larva are lemon yellow and resemble the adult but do not have wings.

Biology: Flower thrips were first described in New York in 1855. In the summer they are found throughout the eastern United States, with maximum numbers migrating into the area approximately the first week of June.

Flower thrips have been reported on 29 plant orders, including day lilies, grass flowers, peonies, privet hedge, trees, vines, and weeds. They seem to prefer grasses and yellow or light-colored blossoms.

They can be seen if an infested flower is shaken over a sheet of white paper.

Beginning with the egg stage, these insects pass through two larval, prepupal, pupal, and adult stages in approximately 11 days in summer months.

Thrips reproduce in weeds, grass and trees throughout the year in North Carolina. Females begin to lay eggs within 1 to 4 days in the summer months and within 10 to 35 days in winter months. Eggs are inserted into flower or leaf tissue. Prepupal and pupal stages are spent in the soil. From there they fly to rose buds where they feed inside the sepals.

For several weeks each summer, beginning the first week of June, the petals of garden roses, especially white varieties, may become brown. Heavily infested rose buds do not open properly. The sepals fold down, but the petals tend to cling together. Lightly infested flowers open, but the outer petals are often distorted and streaked or spotted. Flowers suffering from thrips injury age much faster than healthy flowers. During warm periods, thrips often swarm in late afternoon.

Control: Flower thrips are consumed by green lace-wings, lady beetles, insidious plant bugs, and salamanders.

Control is difficult due to continual migration from grass, weeds, and trees, particularly in May and June. Cheesecloth cages or bags around prized blooms may be practical to protect them from damage. No fully satisfactory chemical control is available because rapidly expanding flowers cannot be kept adequately covered with an insecticide.

ROSE MIDGE
Photo courtesy of Dr. Jim Baker, North Carolina State University


Rose Midges
Order:
Diptera
Family: Cecidomyiidae
Scientific Name:

Description: Rose midges are tiny, yellowish flies which are attracted to new growth of roses, where they lay their eggs in the growing tip of rose stems. The maggots that hatch from the eggs bore into developing rose buds, destroy the tender tissue, kill the tips and deform the buds. When the maggots mature, they drop to the soil and molt into a resting stage called the pupa.

After a few weeks, another generation of adult rose midges emerges from the pupal stage to mate and lay more eggs.

Control: No satisfactory insecticide control is available. The infested tips should be cut and destroyed daily for one month to eliminate the maggots before they complete their growth and drop to the ground. Infested tips should not be discarded on a compost pile because the midge maggots develop in the discarded buds and eventually the adults will fly back to the roses.

INSECTS WITH CHEWING MOUTHPARTS

FULLER ROSE BEETLE
Photo courtesy of Dr. Jim Baker, North Carolina State University


Fuller Rose Beetles
Order:
Coleoptera
Family: Curculionidae
Scientific Name: Pantomorus crevinus

Description: This light-brown to ash-gray beetle has elbowed antennae arising from its snout and a white band on the side of each wing cover. Approximately 7 to 9 millimeters in length, this beetle is unusual because males of this species have never been found and adult beetles cannot fly.

An egg mass is composed of 10 to 60 smooth, pale yellow eggs, each measuring approximately 1 millimeter in length.

Larva are legless, and slightly curved. The body is white, and the head is pale, almost white. When fully grown, it is approximately 9.5 millimeters in length.

Biology: This beetle has been reported from most areas of North America, primarily in California and the South Atlantic states.

The adult and larva of the beetle attack an array of ornamental trees and flowering plants. Adults can be found on azalea, begonia, gardenia, hibiscus, hydrangea, lily, oak. The larva feeds primarily on the roots of blackberry, loganberry, raspberry, rose, and strawberry.

Fuller rose beetle adults feed at night on the leaves of rose leaves, while the larvae feed primarily on the roots. For the most part, Fuller rose beetles overwinter as larvae in the soil, though a few adults have been known to survive the winter. Pupation occurs in spring within 4 inches of the soil surface. Adults first appear in July and continue to emerge through November. The adults produce eggs parthenogenetically and deposit them in small masses around the base of roses. The eggs, which are protected by a white , spongy material, hatch in approximately three weeks. Newly hatched larvae work their way down into the soil to feed on roots. Throughout the growing season, the larvae may be found 3 to 24 inches underground. Only one generation occurs each year.

Control: Fuller rose beetles primarily reduce the aesthetic value of plants. However, if excessive foliar damage occurs, effective pesticides are available. Consult the current North Carolina Agricultural Chemicals Manual for recommendations.

ROSE CHAFERS
Photo courtesy of Dr. Jim Baker, North Carolina State University


Rose Chafers
Order:
Coleoptera
Family: Scarabaeidae
Scientific Name: Macrodactylus subspinosus

Description: Adult rose chafers are tan, slender beetles with reddish heads and long, spiny, reddish legs. They are 8 to 13 millimeters in length.

Eggs are oval, shiny, and white. They are approximately 1 to 2 millimeters long.

Larva are up to 18 millimeters in length and resemble white grubs.

Pupa are light yellow-brown and approximately 16 millimeters long. The last larval skin clings to the posterior of the pupa.

Biology: Rose chafers are found primarily in the northeast, especially in areas of light, sandy soil. They also occur south at least to North Carolina and west to Colorado.

Although these beetles prefer the flowers of roses and peonies, they also feed on apple, cherry, dahlia, elder, elm, foxglove, geranium, hollyhock, hydrangea, pear, poppy, Virginia creeper, and wisteria. Grubs feed on roots of turf, weeds, and nursery stock.

Adults appear suddenly, in late May or early June. They live for about 4 to 6 weeks. Eggs are laid about 15 centimeters deep in sandy or grassland soil, and they hatch in 1 to 3 weeks. The eggs are laid in groups of 6 to 40, but each egg is deposited in a separate cavity. The larvae feed on the roots of turf and ornamental plants. They apparently move down into the soil for moisture. The larvae spend the winter deep in the soil. In early spring the grubs migrate upward and pupate in early May in earthen cells. There is one generation per year.

Control: Rosebushes may be protected by a cheese-cloth frame during the time beetles are in flight (most of June). Handpicking the beetles may be effective when practical. Insects are poisonous to poultry and pets. Consult the North Carolina Agricultural Chemicals Manual for current control options.

Japanese weevils

Order: Coleoptera
Family:Curculionidae
Scientific Name: Pseudocneorhinus bifasciatus

Description: Japanese weevils range in size from 4.5 to 7 mm. They are light or dark brown with a short blunt snout. Wing covers are striped with indistinct white lines in the grooves, white spots on the apical half, and a dark brown or black transverse band.

Biology: Japanese weevil larvae feed on plant roots, but the adults do more serious and apparent damage. The weevils feed extensively on new leaves, shoots, and inner foliage. As a result, infested plants are tattered and unhealthy in appearance. Unlike most weevils, the Japanese weevil tends to feed during the day. If disturbed, they drop to the ground and remain motionless.

It is assumed that the Japanese weevil is parthenogenetic because no males have been recorded. Eggs are deposited in folds along the margins of leaf fragments or dead leaves, and the free edge is sealed to form a pod. When the eggs hatch, the larvae burrow into the ground and feed on the roots. These weevils have fused wing covers and are unable to fly. There is only one generation each year.

Japanese weevils are resistant to many insecticides. Consult the North Carolina Agricultural Chemicals Manual for current insecticide recommendations.

JAPANESE BEETLES
Photo courtesy of Dr. Jim Baker, North Carolina State University


Japanese beetles
Order:
Coleoptera
Family:
Scarabaeidae
Scientific Name: Popillia japonica

Description: Japanese beetles are attractive, metallic green beetles approximately 3/4 inch long. They have coppery brown wing covers. Six small patches of white hairs appear along the sides towards the rear of the insect. The male and female look alike, but the male is generally smaller and has sharper spines on its forelegs.

The larva is a C-shaped, white grub with a yellowish-brown head. When fully grown it is approximately 25 mm long. It is usually found in a cell underground.

JAPANESE BEETLE GRUB
Photo courtesy of Dr. Jim Baker, North Carolian State University


Biology: Although over 300 plants are recognized foodsources for this beetle, the adults are particularly fond of white and yellow flowered roses.

Both the larvae and adults have chewing mouthparts. Larva consume roots of turfgrass, while adults are strongly attracted to open rose blossoms, leaves, and buds. Adults do not eat leaf veins, and therefore skeletonized leaves are indicative of this beetle.

Japanese beetles overwinter as larvae, pupate in late spring, and emerge as adult beetles about two weeks later. Adults usually appear in mid-May. They are gregarious, often feeding together in masses on flowers, and foliage. They fly in broad daylight. Populations diminish during August.

Control: Insecticides will not completely protect roses, which unfold rapidly. When beetles are first noticed, buds should be nipped and bushes treated with a labeled insecticide. When the beetle population diminishes, the bushes can be allowed to bloom.

In heavily infested areas, covering the blooms with cheesecloth cages or netting may be required to prevent the beetles from alighting on the flowers. If Japanese beetle traps are used, they should be located away from roses, otherwise, the trap will attract beetles to the roses.

Consult the North Carolina Agricultural Chemicals Manual for current insecticide recommendations.

Miscellaneous rose pests

Old rose stems sometimes become encrusted with white insects known as rose scale . These insects suck sap from the plants. Dimethoate spray applied at least once every two weeks during the summer will reduce the number of scales by killing the young rose scale crawlers. If scales persist until fall, prune out the stems that are most severely infested. During the dormant season, spray the remaining stems with a summer-oil emulsion.

The rose leaf beetle is a small, metallic green beetle that feeds in the buds and on the flowers of roses, often riddling them with holes. The insects are most numerous in suburban gardens near uncultivated fields.

In late summer moths of field crops are often attracted to roses to lay their eggs. Tobacco budworm eggs are small and pale. Soon a tiny worm will hatch from the egg and feed on the bud, sometimes tunneling straight into the bud. One or two tobacco budworms can destroy the beauty of a rose.

SADDLEBACK CATERPILLAR


The saddleback is a stinging caterpillar, which is sometimes abundant on rose leaves. When one brushes against a saddleback, the effect is like brushing against a Portuguese man-o-war. Saddleback caterpillars spin a cocoon when they mature and develop into pupas and then into adult moths. The moths mate and then lay eggs for another generation.

Puss caterpillars also feed on the leaves of roses. Puss caterpillars also have stinging hairs.

Woollybear caterpillars sometimes feed on rose leaves. They do not sting.

Obliquebanded leafrollers are difficult to control, because they tend to tie rose leaves together and feed in between.

Ceratina carpenter bees are small carpenter bees that forage for pollen and nectar. These bees bore into rose stems after pruning or flower cutting. To control carpenter bees, use tree paint or wound dressing to cover the stubs made during pruning or cutting flowers. Eventually, the adult carpenter bees will leave the area to search out suitable stems for nesting.

LEAF CUTTER BEE DAMAGE
Photo courtesy of Dr. Jim Baker, North Carolina State University


Leaf-cutter bees cut circular pieces from rose leaves and other plants and store them as food for their young in burrows dug in the pith of rose stems, broken branches, or in plant crevices. The tunneled stems usually die back for several inches.

No satisfactory insecticide control is available for these bees, which are valuable as pollinators of alfalfa and other plants. A carpet tack pushed into the end of the cut stem at pruning time will prevent the bees from entering and tunneling the stems. Tree-wound paint can also be applied to the ends of the cut stems.

Several species of wasp-like insects lay their eggs in stems of roses and their larvae cause large swellings or galls. One species makes a gall resembling fibrous moss on the stem. Another causes a large wart-like gall near the ground surface. These galls may be confused with the crown galls caused by bacteria. However, if insect galls are cut open, numerous larvae, or the cells in which they develop, will be visible.

No known insecticide will control the insects that produce these galls. The best available control is to prune the infested stems to remove the galls and bury them promptly to destroy the larvae in the galls before they emerge.

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Last Modified: 07/10/96