Lacewing Larvae Come With Jaws

A green lacewing looks like something you would put on a greeting card. Its larva looks like something the greeting card should be warned about.

The adult has delicate, netted wings. The larva—the young stage—is a small, crawling predator with curved jaws projecting from its head. Those jaws catch other small animals, especially aphids. Among the insects on an infested plant, the one that looks most alarming may be eating the ones doing the damage.

That makes lacewing larvae worth recognizing before you start removing bugs. They are often called aphid lions, and they look very little like the adults they will become. The word “green” is your first misleading clue.

What do lacewing larvae look like?

Green lacewing larvae are usually cream, tan, grayish, or brown, often with darker spots or stripes along the back. A typical larva has a flattened, elongated body that narrows toward the tail. Six jointed legs attach just behind the head; there are no fleshy walking feet along the abdomen like those of many caterpillars.

The most useful feature is at the front: two long jaws that curve inward like open pincers. Color and markings vary, but those projecting jaws are a much better clue.^{1, 2}

Curved jawsSix thoracic legsTapered abdomen

Size changes as the larva grows. In Chrysoperla, a common group of green lacewings, a hatchling starts around a millimeter long or less and may reach about ¼–⅓ inch. The tiny, pale youngster and the conspicuous predator in a close-up photograph are the same insect at different ages.³

Ladybug larvae have a similar little-alligator shape, but lack the lacewing’s long, sickle-shaped jaws. Brown lacewing larvae are a closer lookalike: they also have curved jaws and include useful predators. “Brown lacewing” names a different family, not simply a green lacewing whose larva happens to be brown.^{2, 8}

When the larva looks like moving debris

Not every lacewing larva wears its identifying features in plain sight. Some collect plant fragments, insect remains, and waxy material from prey, then carry the pile on specialized bristles along their backs. The head and legs may be all you can see underneath.

The covering can conceal or shield the larva from enemies. A lacewing may hunt aphids, but it can be attacked itself—including by ants on the plant. The debris is protection, not evidence that the insect needs cleaning.^{1, 9}

Researchers have documented everything from exposed larvae to elaborate debris carriers across the green lacewing family. Chrysoperla larvae generally go without the packet. These are different ways of being a lacewing larva, not stages every larva passes through.⁴

This matters when a white or dusty-looking speck starts walking. A debris-covered predator can be mistaken for a pest and wiped away with the insects it was hunting. Look at the creature beneath the covering: an exposed head with curved jaws is a very different clue from a patch of white material alone.

What do lacewing larvae eat?

Green lacewing larvae hunt small prey they can catch and pierce. Aphids are a familiar meal. Depending on the lacewing species, the menu can also include young whiteflies, thrips, mites, small scale insects and mealybugs, insect eggs, and small caterpillars.^{5, 6}

Those curved jaws explain how they feed. A larva grips and pierces its prey, introduces digestive fluids, and draws the liquefied contents through its mouthparts. It does not chew an aphid into pieces. This is a very small predator with a rather efficient approach to soup.⁶

But a long menu does not mean every pest on a plant is equally easy to eat. The prey must be small enough to handle and accessible to the jaws. An exposed aphid presents a different opportunity from an insect beneath a protective covering or hidden inside plant tissue.

Even the leaf surface can get in the way. Cornell’s review notes that hairy or sticky leaves can make prey harder for lacewing larvae to find, and that aphid control varies among crops. An impressive appetite is only useful when the hunter can reach the meal.³

A lacewing feeding on a pest is therefore useful evidence of predation, not proof that the whole infestation is handled. Recognizing the predator and assessing the pest problem are two separate jobs. You can leave the hunter in place while continuing to watch what is happening to the plant.

Their menu can include each other

That appetite is not reserved for insects we dislike. Lacewing larvae can eat other predators, including smaller lacewing larvae. “Beneficial” is our description of what they do for us. It is not a code of conduct they have agreed to.

Food availability helps determine how often those encounters turn into meals. In experiments pairing two green lacewing species, increasing the supply of aphids generally reduced both cannibalism and attacks on the other species.⁷ A hungry neighbor is a different proposition when there are aphids within reach.

If you introduce eggs or larvae to infested plants, distribute them across the foliage rather than concentrating them in one heap. Spreading them out reduces crowding and places the emerging hunters nearer their prey.⁹

The hunting stage does not last forever

All that feeding supports the larva’s growth, but it will not remain a larva. Green lacewings develop through four stages: egg, larva, pupa, and adult.

Green lacewing eggs laid on plants stand on fine silken stalks. After hatching, the larva passes through three growth stages, called instars. It then makes a small silk cocoon and pupates inside. The next insect to emerge has wings.¹

Top left · EggTop right · LarvaBottom left · CocoonBottom right · Adult

In Chrysoperla, that transformation also changes the diet. Adults feed on pollen, nectar, and honeydew—the sugary material produced by aphids and other sap-feeding insects. Other groups of green lacewings include predatory adults, so the change is not universal across the family.¹

For Chrysoperla, however, a plant full of aphids provides food for the hunting larvae without necessarily meeting every need of the adults. Flowering plants can provide adult food that supports reproduction, and the winged insects can travel elsewhere to find it. A larva’s feeding place need not be where the rest of its life happens.³

Recognize the help before removing it

The jaws, the debris packet, and the stalked eggs all matter for the same practical reason: useful insects do not arrive wearing a label. An infested plant can hold both the animals damaging it and the animals eating them. Treating every unfamiliar insect as another pest can remove part of the help already there.

If you recognize a lacewing larva among aphids, leave it where it is feeding. That does not mean ignoring the aphids or assuming one predator will finish the job. It means making the next decision with a better understanding of who is on the plant. Broad-spectrum insecticides can kill natural enemies along with pests, so spraying the whole plant may remove both hunter and prey.¹

The same recognition protects more than the feeding stage. Stalked eggs have not begun hunting yet, and a cocoon shelters the insect as it transforms into an adult. Knowing the life cycle gives those stages a chance to become the insects you would otherwise be pleased to find.

The jaws look alarming. For the aphids, that is an accurate assessment.