Lacewings are insects in the order Neuroptera, sub-order Planipennia. Lacewings are named after the fine, complex, cross-branched venation of their four wings, which presents a beautiful, lacelike pattern. Lacewings are rather poor, fluttery fliers. When at rest, they hold their wings tentlike over their back.
Lacewings have a complete metamorphosis, with four life history stages: egg, larva, pupa, and adult. The eggs of lacewings are laid on vegetation, and occur singly at the end of a long stalk. The aquatic larvae are predators of other invertebrates. The larvae of some species of lacewings cover themselves with organic debris as a form of protective camouflage.
Adult lacewings are commonly found in vegetation, usually in the vicinity of surface waters such as streams and ponds. At night, lacewings are often attracted to lights in large numbers. Adult lacewings are terrestrial, and most species are predators of other insects. Some species are important predators of aphids (family Aphididae, order Homoptera) and other soft-bodied insects, and they can be beneficial by helping to prevent those sap-sucking insects from maintaining populations that are injurious to economically important plants.
The most abundant lacewings in North America are the greenish-colored, common, or green lacewings (family Chrysopidae), sometimes known as aphid-lions because of their voracious feeding on herbivorous insects. These lacewings can be quite abundant in herbaceous vegetation near aquatic habitats, and when handled they may give off an unpleasant-smelling odor. Chrysopa californica is a western species that has been mass-reared and used as a biological control of certain species of mealybugs (family Coccoidea, order Homoptera) in agriculture. The brown lacewings (family Hemerobiidae) are another relatively common group, while the pleasing lacewings (Dilaridae), beaded lacewings (Berothidae), ithonid lacewings (Ithonidae), and giant lacewings (Polystoechotidae) are relatively rare groups.