Photo Gallery of Insects and Mites on Ornamental Plants
Blue winged wasps are black with a metallic blue highlights on the wings and thorax. The abdomen has two yellow spots near the middle and the tip is reddish-brown in color. Blue winged wasps are often noticed flying low over the lawn in loops and figure-eight patterns. This attractive wasp is a parasite of green June beetle grubs. When green June beetles become abundant, the blue winged wasps may also become more abundant the following year. Female wasps burrow through the soil in search of grubs. After stinging the green June beetle grub, she lays an egg on it. When the blue winged wasp grub hatches, it consumes the green June beetle grub alive! Sometimes these wasps are quite abundant and conspicuous as they swarm during their mating dances. Later, females spend more time digging for grubs and the swarms are not as noticeable. These wasps forage for nectar and sometimes sleep on plants. As the nights cool off, they burrow under the soil at night. Scoliids do not have any sort of nest-guarding instinct. The only hazard they represent is to barefoot humans who might inadvertently step on one or to those unwise enough to molest these otherwise beneficial insects.
One of the velvet ants is called the cow killer because of its amazing stinger. This handsome insect squeaks audibly (especially when stepped on) and is exceptionally tough. However, the squeaks of the cow killer would be drowned out by painful screams if the person stepping on the wasp was barefooted! Velvet ants are parasitic wasps. The females are wingless and resemble hairy ants. Female velvet ants seek out a host nest and lay their eggs on the host larva. The velvet ant larvae consume the host wasp larvae and pupate and mature into another generation of velvet ants. The cow killer parasitizes the nests of a large black, yellow, and orange solitary wasp called the cicada killer. The cicada killer provisions its nest with cicadas that the cicada killer larvae eat. Cow killers slip into the host wasp nest, lay their eggs, and depart. The exceptionally tough exoskeleton of the cow killer protects it from stings of the host wasp in case they meet in the nest. Velvet ants are not usually numerous, and no control measures are usually needed. However, one of the commercial aerosols of bee and wasp spray or one of the flying insect aerosols will kill this insect.
The lesser canna leafroller is a small caterpillar related to the European corn borer, pickleworm, coneworms, sod webworms, and others. The lesser canna leafrollers overwinter as larvae in the leaves and stems of canna and the moths emerge to mate and lay eggs after the new growth emerges in the spring. When the larvae hatch, they feed within the new, still-rolled leaves. Older larvae can actually tie the edges of older leaves together and roll the leaf back up! The lesser canna leafroller is evidently not cannibalistic as several caterpillars can be found feeding inside one rolled leaf. The lesser canna leafroller caterpillars only feed on the upper epidermis and mesophyll. If not managed, lesser canna leafrollers may completely destroy the aesthetic value of cannas. One mistake canna growers make is to leave the old dead growth on the canna bed as a sort of mulch. Canna seems to be the only host plant for this pest, so that if the plants are somewhat remote from other cannas, it may be possible to drastically reduce the lesser canna leafrollers just by carefully removing all dead leaves and stems in the fall after the frost has killed it back. It is possible to eradicate this pest by using Orthene as a spray several times, perhaps at ten-day intervals. The Bacillus thuringiensis insecticides are also effective for this pest. Spray the dilute pesticide mixture directly downward into the rolled leaves so that the pesticide can soak into the shelter around the caterpillars. Also pick up and destroy all of the dead tops from the cannas this winter after the frost.
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Last modified on August 16, 1999 by Stephen J. Toth, Jr.