Lacewing larva, often called a trash bug or garbage bug.
Anna Sara Hill, ©2024, Clemson Extension
What is This Little Critter?
This is a lacewing larva, often called a trash bug or garbage bug. They collect insect molts, dead insects, bits of leaf debris, bark, lichens, spider webs, and other material from their environment. The material is woven and tied into a hemispherical mass and carried on their backs. The larvae repair and reconstruct their bundles frequently, so it is always tidy and there are no loose ends. The trash is held in place by fan-like hairs on the side of the abdomen.
How Do Lacewing Larvae Construct Their Trash Mass?
Lacewing larvae are extremely agile and can move their heads horizontally over the back of their bodies. This allows them to use their jaws to assist with placing the small bits of debris onto their backs and tuck the loose ends into the mass. They start making the mass at the back end and add to it on the front. As it gets larger, they push it back, and eventually, their whole body and part of their head is covered.
Why Do Some Lacewing Larvae Cover Themselves with Trash?
Not all species of green lacewings cover themselves with trash. Those that do have less chitinized epidermis and more translucent bodies. It is speculated that the mass of trash protects the body from desiccation and mechanical injury, as well as disguising the larvae from predators and parasitoids. An added benefit of the disguise is that it makes the larvae less recognizable to its prey.
What Do Lacewing Larvae Eat?
Green lacewing larvae are voracious predators of soft bodied insects such as aphids, mealybugs, soft scales, thrips, whitefly nymphs, mites, and other small soft bodied insects. The mandibles and maxilla of lacewings are fused, forming a specialized hollow jaw like a straw. The larvae grasp its prey with long-curved, pointed mandibles and tear it by moving it back and forth, simultaneously injecting pre-digestive enzymes from venom glands located at the base of the maxillae. The enzymes paralyze and liquefy the organs of the insect. The liquified prey is then sucked up by the larvae. In most species of green lacewings, the adults feed on pollen and nectar and occasionally snack on aphids.
How Can Lacewings Be Used in Biocontrol?
Lacewings’ insatiable appetite make them effective biocontrol, and they can be used in combination with cultural, physical, and mechanical practices in a successful IPM program. Avoid the use of broad-spectrum insecticides, which will kill beneficial insects such as green lacewings, as well as pests. Alter the environment to attract lacewings naturally, and if population levels need boosting, implement a release program. Green Lacewings are reared and sold by several commercial companies. They can be purchased at all life stages. If releasing them, ensure that there is a ready food supply, including nectar plants for the adults. Also, check guidelines for the best time of day and the temperature range at which they should be released. Release techniques will vary depending on the life stage. Proper planning and knowledge of the life stages of both the pest and Lacewings are needed for a successful release.
