Most of the insects in the order Neuroptera are predators in the larval stage; some also are predators as adults. The adult insects in this group are characterized by having soft, slender bodies, well-developed antennae, and large membranous wings that are richly endowed with a nerve-like network of veins (neuro + ptera = nerve wing). This group has a rather modest number of species within a relatively few families, but they are very important in natural and biological control, especially the lacewings.
The adult green lacewings have a soft, slender, green body, large membranous wings with green veins, and long hair-like antennae. The overall body length, including wings, is about 1 inch; some common species have golden eyes. Sometimes these insects come to lights at night. The eggs are small, greenish to white in color and laid on hair-like stalks about 1/3 inch high. The larvae are somewhat elongate, up to about 1/3 inch long when fully grown, broadest in the middle and tapered toward the rear. The larvae have noticeable sickle-shaped mouthparts. When fully grown, larvae pupate within spherical, parchment-like silken cocoons. It takes four to six weeks to complete a generation.
Green lacewings tend to specialize in feeding on aphids and usually the adults lay their distinctive eggs near aphid colonies. However, the larvae feed on many types of soft bodied insects, including mealybugs, scale insects, leafhoppers, thrips and even small caterpillars. They can detect the larvae of leafminers actually within the mines. The larvae will pierce the leaves in order to feed on the miners within. They are also good predators of spider mites.
Different species will tend to search in different habitats; some prefer low-lying herbaceous plants or grasses whereas others tend to be more arboreal. Lacewings are very common and important naturally occurring predators in many crops, on landscape plants and in the home garden. However, they are also available commercially for augmentation biological control. The stage usually purchased and released is the egg, but some companies also provide partially grown larvae and adults. Ask your supplier to recommend the most appropriate species and stage for your pest management needs. Adult lacewings all require carbohydrate-rich foods such as aphid honeydew or flower nectar; the adults of some species are not predators.
The adult brown lacewings resemble green lacewings, but are generally smaller and brown. Superficially, the larvae are similar to those of green lacewings, but the mandibles are not so prominently developed. The eggs are not stalked as in green lacewings. Brown lacewings can be found in many habitats but may be more frequently found as predators within tree canopies. Studies have shown that some brown lacewing species are restricted to certain tree types. One species may occur on oaks while another occurs on pines in the same area. They feed primarily on various types of Homoptera, such as aphids, mealybugs, scale insects and the nymphs of whiteflies. They are not commercially available.
The dusty wings are among the smallest of the Neuroptera; adults are only about 1/4 inch or less. The common name of the family is derived from the presence of a white- to- grayish powdery wax that covers the wing surfaces. Dusty wings are not common insects but they are more numerous in the southern United States. They feed on small prey such as aphids, scale insects and spider mites. Occasionally they are abundant when there are outbreaks of their prey.
Most other families of Neuroptera are also predatory or parasitic, especially in the larval stage. Many of these have interesting biological habits but are not important in biological control of pests.
The Myriueleontidae are the antlions. Adults are similar to damselflies in general appearance but have clubbed antennae and are feeble, nocturnal fliers. The larvae, or doodlebugs, have long, sickle-like jaws. Each larva hides at the bottom of a small conical pit made in sand or dust and feeds on ants or other insects that fall into the trap. They tend to be more common in the southern part of the United States.
Members of the family Ascalaphidae are called owlflies. The habits are similar to those of antlions, but the larvae only cover themselves with dust for concealment, rather than digging pits.
The Mantispidae are reminiscent of praying mantids. They have large raptorial front legs for grabbing and holding prey. The larvae are predaceous on spider egg sacs.
Dan Mahr, University of Wisconsin, Madison
Taken from Midwest Biological Control News, Vol. V, No. 4.
Published in Hort Impact July 1998
Images created by Jim Kalisch provided courtesy of UNL Dept. of Entomology
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