Why these hairy, tent-building moths are named after woolly caterpillars and egg-shaped cocoons.

Nature · Published 3 October 2026 Swipe more like this →

In short: Lasiocampidae moths, known as eggars or lappet moths, are a diverse family of over 2,000 species. From their unique snout-like mouthparts to the silk nests of tent caterpillars, these large, hairy insects have evolved fascinating survival strategies, including camouflaging their cocoons to blend perfectly with the trees they inhabit.

The name Lasiocampidae is derived from the Greek words lasio, meaning woolly, and campa, referring to the caterpillar. This nomenclature highlights the most striking feature of the family's larvae: they are typically large and heavily covered in hair, particularly along their sides. Many species also possess distinctive skin flaps on their prolegs, which earn them the common name lappet moths, and a pair of dorsal glands on their abdomens. These caterpillars are voracious feeders, consuming the leaves of various trees and shrubs.

The family is perhaps best known for its diverse reproductive and social behaviors. Some species, famously called tent caterpillars, construct elaborate communal nests spun from silk. In these species, females deposit their eggs in masses, sealing them with a protective material that hardens upon exposure to air. Other species are known as eggars, a name inspired by the neat, egg-shaped cocoons they weave. These cocoons are often masterfully camouflaged using the same plant material from which the larvae fed, providing a layer of protection against predators during their transformation.

As adults, these moths are generally large-bodied with broad, often brown or grey wings. Their physical characteristics are highly specialized; some retain elongated, snout-like mouthparts, while others have reduced mouthparts and do not feed at all during their adult stage. They exhibit both diurnal and nocturnal activity patterns. Despite their diversity, they share common traits such as hairy bodies and legs, and bipectinate antennae in both sexes. While over 2,000 species have been identified, experts suggest that many more remain unstudied or unnamed, leaving much of this family's evolutionary history and biological complexity waiting to be discovered.

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