Photo Gallery of Insects and Mites on Ornamental Plants
The Lantana lace bug, Teleonemia scrupulosa, was found damaging lantana in New Hanover County earlier this week. Mr. Bob Blinn, curator of the North Carolina State University Insect Collection, performed the determination. This is a new state record for North Carolina. The lantana lace bug is native from Florida across to Texas and southward into Brazil. Lantana is used as an ornamental plant here, but in areas further south lantana is a weed that forms dense, spiny thickets on large areas of land. The lantana lace bug has even been introduced into other countries for biological control! Lantana lace bugs can actually defoliate lantana. These insects grow through five dull, spiny, nymphal stages in about 2 weeks. The 3 or 4 mm long adults start laying eggs after 5 or 6 days. The eggs are inserted into the lower leaf surface in groups of 10 to 30. Lantana is the only host plant on which the lantana lace bug causes any significant damage.
Redbud leaffolders are small caterpillars that apparently feed only on redbud. They fold a part of a leaf over or web adjacent leaves together to feed within the shelter formed. There are two generations each summer. The adult is a small, black moth with white spots. The moths are extremely active and run, jump, and fly readily when disturbed. The caterpillars are black with white markings (or white with black markings depending on your view). When leaves are pulled apart, the caterpillars usually go into a frenzy of thrashing about and drop to the soil. Because they fold the leaves together tightly, it may be best to use a systemic pesticide such as Orthene. Whatever pesticide is used should be sprayed thoroughly to soak where the leaffolders are feeding.
The larvae of southern pine sawyers make an noticeable clicking or rasping noise as they tunnel through dead or dying pine trees, and they push sawdust-like frass from the tree. This is the insect that homeowners hear when they call and claim they have pine bark beetles because they hear them in there chewing. Sawyers are abundant in North Carolina, and they are very sensitive to the health of pines. Soon after a pine tree reaches the point of no return, adult sawyers fly to it and chew holes in the bark in which they lay eggs under the bark. Sawyer larvae hatch and bore in the sap wood for a while and then tunnel directly into the heart wood and tunnel back and forth before pupating about a year later. One reason pines are best cut in the winter for log homes is that logs are cut during warm weather are inevitably infested by sawyers that soon degrade the wood with their tunneling. Some can actually survive milling and planing as long as the blades miss them. As the wood dries out, development slows so that the adults may not emerge for several years (and then may bore out through the sheet rock or through the flooring!). There is no practical way to control sawyers other than keeping pines in good health (avoiding soil compaction, irrigating in dry weather, fertilizing according to a soil test, etc.).
Spider mites are tiny arthropods that insert their tiny, scissor-like mouthparts into leaves and petals and cause tiny yellow spots to form as they suck out the contents of the plant cells. Predaceous mites and small lady beetles feed on spider mites and parasitic fungi infect these mites, especially in humid weather. Hot, dry weather apparently inhibits the parasitic fungi and accelerates the life cycle of the spider mites. Daylilies, roses, butterfly bush, some euonymus and bedding plants are often infested by spider mites during the summer. Because spider mites flair up in dry weather, their control is somewhat difficult because plants that are wilted are much more susceptible to pesticide injury than turgid plants. Because spider mites are tiny and relatively fragile, they can be dislodged from ornamental plants by watering the plants with an ordinary garden hose. Many of the dislodged mites will drown. There is a problem with this method, however. If the plant is tender, the stream of water may bruise or break it. Horticultural oils and soaps are moderately toxic to spider mites. Ornamentals and Turf Insect Information Note No. 25 explains more spider mite biology and control.
For the rest of the summer, junipers and other landscape plants infested with the spruce spider mite will have characteristic eggs or egg shells of the spruce spider mite, but no mites. Spruce spider mite eggs are round, but slightly flattened horizontally and have a diagnostic stipe (thread) projecting up from the center. Spruce spider mites seem to die in hot weather (the eggs survive the summer in the Piedmont and Coastal Plain of North Carolina). Spruce spider mites do most of their damage in spring and fall, but often the foliage does not turn yellow-brown until June or July after the mites have died. There is no need to spray with conventional miticides, but Morestan and Joust are labeled for mites and mite eggs. There is additional information on the biology and control of spruce spider mites in Ornamentals and Turf Insect Information Note No. 77. Ornamentals and Turf Insect Information Note No. 57, the Juniper Pest Management Calendar may be of interest and remind landscapers when to scout for spruce spider mites.
The western flower thrips can transmit impatiens necrotic spot virus and tomato spotted wilt virus to ornamental plants. It overwinters in North Carolina as well as areas further south. One threat to greenhouse plants is that larvae of western flower thrips outside the greenhouse may pick up tomato spotted wilt virus from infected weeds, and then new adults can fly through the evaporative cooling pads into greenhouses where they can then spread the virus among susceptible crops. Another threat is that western flower thrips may blow into greenhouses and become established (because of its great pesticide resistance) and later a plant with impatiens necrotic spot virus may be brought in and the virus acquired by immature western flower thrips and spread through the rest of the range by the new, infected adults. Conserve is the most effective pesticide for western flower thrips management currently labeled for ornamental plants. Conserve is a relatively new pesticide from Dow Agrosciences. To slow down the acquisition of pesticide resistance, they recommend applying Conserve only once per 13-week crop. Other pesticides labeled for western flower thrips control are included in the North Carolina Agricultural Chemicals Manual. Ornamentals and Turf Insect Information Note No. 72 provides more information on the biology and suppression of western flower thrips.
The following information was obtained when scouting container nurseries in Wake County. Pest development will be more advanced south and east of Wake County, and less advanced north and west of Wake County.
An outbreak of powdery mildew was found on Euonymus spp. Begin scouting susceptible plants for the symptoms of powdery mildew, a powdery white to light gray fungus found on stems, leaves, buds and/or flowers. (Reference: http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin004/odin004.htm)
Adult Japanese beetles continue to emerge. Although not specifically noted in this week's nursery scouting, we have observed Japanese beetle adults in several locations this past week. (Reference: http://www.ces.ncsu.edu/depts/ent/notes/Ornamentals_and_Turf/flower_contents/orn_t44/not44.html)
Ladysthumb (Polygonum persicaria) and oxalis (Oxalis corniculata) were found in flowers. Remember that oxalis seed pods can mature even after you have pulled the weed. So be sure to remove weeds from the site immediately after weeding. (References: http://www.css.msu.edu/css362/page34.html and http://www.agf.gov.bc.ca/croplive/cropprot/weedguid/ladysthm.htm)
The hot, dry weather has given chinch bugs a big jump in St. Augustinegrass. Be aware that the populations of this pest have already started to increase and expect to see serious damage in many St. Augustinegrass lawns by the end of June. Rainy weather is the best solution for this pest problem.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on June 14, 1999 by Stephen J. Toth, Jr.