Have you seen these long, slender insects at night, perhaps clinging to your house near a porch light? They’re lacewings—delicate, mostly harmless insects that feed on pollen and nectar as adults. But in their larval stage, they’re fierce predators of aphids, mites, mealybugs, and other plant pests. In other words, lacewings are very beneficial.
Lacewings belong to the order Neuroptera, which includes mantisflies and antlions. The name comes from the Greek neûron (“nerve”) and ptérux (“wing”), referring to their transparent, finely veined wings—easy to recognize at a glance.
Fossils show that lacewings first appeared around 290 million years ago during the Permian Period, having evolved from even older ancestors. Today, about 2,000 species exist worldwide, found on every continent except Antarctica. Most are either green lacewings (Chrysopidae) or brown lacewings (Hemerobiidae). About eighty-five species of green lacewings and sixty species of brown lacewings inhabit the United States.
Green Lacewing (Chrysopa chi) (Brad Smith/Flickr; CC BY-NC 2.0)
Green lacewing adults are usually bright green to greenish-brown, while brown lacewings are typically grayish-brown. Both groups have large, compound, metallic-gold eyes, especially green lacewings, and it’s possible they see in color. Some also have simple eyes (ocelli). Lacewings also have the other basic senses. Their antennae, mouthparts, feet, and scattered hairs on their body have receptors for taste, smell, and touch. They “hear” by detecting vibrations. They have two pairs of wings, but when they fly, it’s weak, merely a graceful flutter.
Brown lacewings tend to be more cold-tolerant and often appear earlier or later in the year than green lacewings. Their larvae are predatory—smaller than those of green lacewings, but still effective.
Brown lacewing, Hemerobiidae sp. (Judy Gallagher / Flickr; CC BY 2.0)
During the day, lacewings usually rest on the undersides of leaves, wings folded tent-like over their bodies. They’re found wherever their larvae can find prey—in gardens, meadows, forests, and agricultural fields. The larvae are sometimes called “aphid lions” for their voracious appetite, but they don’t limit it to aphids—they’ll attack a wide range of other small, soft-bodied insects, such as mites and whiteflies. Because of this, some farmers and gardeners purchase lacewing eggs to use as a natural pest control method.
Green lacewing eggs with aphids nearby (Douglas Mills/Flickr; CC BY-NC-ND 2.0)
Lacewings mate in late spring and summer, but humans can’t hear their mating calls without special equipment. Their eggs are laid on thin silk stalks, each about 0.3 inches (8.4 mm) long, typically under a leaf near aphids or other food sources. That way, the larvae have something to eat as soon as they hatch, which is from three days in warm weather to ten days, if it’s cooler. Some species lay eggs singly, while others deposit them in tight clusters. Each egg is the size of a pinhead, and the stalks are hair-thin. As the eggs darken, hatching is near. There are several generations each year, and the final ones usually hibernate through winter, either as pupae or adults, tucked away in leaf litter or other sheltered spots.
Green lacewing larva (Chrysoperla sp.) (Katja Schulz/Flickr; CC BY 2.0.jpg)
Send a mental salute when you see a larva— it’s helping to control aphids, mealybugs, and other pest insects on your plants. During the day, lacewings usually rest on the undersides of leaves, wings folded tent-like over their bodies. They’re found wherever their larvae can find prey—in gardens, meadows, forests, and agricultural fields. The larvae are sometimes called “aphid lions” for their voracious appetite, but they don’t limit it to aphids—they’ll attack a wide range of other small, soft-bodied insects, such as mites and whiteflies. Because of this, some farmers and gardeners purchase lacewing eggs to use as a natural pest control method.
Of course, lacewings themselves are also prey. They’re not intelligent, but they show instinctive behaviors that are impressively fine-tuned for survival. One is their interesting defense against bats: when adults hear a bat echolocating nearby, they drop out of the air and fall to the ground, wings folded—a literal act of “lying low” to escape detection. And if you spot what looks like a tiny, mobile pile of lint or sand creeping across a leaf, you might be watching a lacewing larva in disguise: some species use debris, molted exoskeletons, or even the bodies of their prey as camouflage—a kind of movable armor to protect against birds and other predators.
Camouflaged Green Lacewing (Chrysopa sp.) (Katja Schulz/Flickr; CC BY 2.0)
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