Lacewings are close relatives of dobsonflies and fishflies, all found within the insect order Neuroptera, also known as the net-winged insects. Photo: Amy Korman, Penn State
Most lacewings overwinter as pupae, but some species overwinter as adults. One group of lacewings, the common lacewings, are found throughout Pennsylvania as well as other areas of the country. Over 80 species are species known in North America. These common lacewings are an essential group of beneficial insects, particularly the immature stages that are predators of many common garden and greenhouse pests: aphids, scales, caterpillars, whiteflies, mites, and others.
Immatures are often referred to as “aphid lions” due to their hearty appetite, predacious nature, and the ability to eat enormous numbers of aphids. As adults, many species feed on pollen and honeydew; however, some species are predators as adults. Eggs are laid singly or in clusters; the long stalk is a key characteristic of lacewing eggs. When deposited on plants, eggs are often on the underside of leaves, but I have also seen them on wooden house siding and other surfaces. Lacewing adults are active in the evening and can be attracted to lights.
Note the slender stalk attached to this lacewing egg. Photo: Amy Korman, Penn State
As with many other beneficial insects, a diverse collection of flowering plants will attract lacewings to the garden and keep them happy. Since many lacewing adults feed on pollen, plants such as coreopsis, cosmos, and angelica, as well as others, will encourage the lacewing population. Lacewings are one of several beneficial organisms that are available for purchase from commercial producers in the United States.
These are great insects to have in the landscape, but they are also susceptible to many commonly used insecticides used in the ornamental setting, including some of the “softer” insecticides. Any use of pesticides must be thoughtfully considered if one of the landscape goals is to encourage populations of beneficial organisms. Read pesticide labels before use and always carefully follow the instructions.