Tent caterpillars are moderately sized caterpillars, or moth larvae, belonging to the genus Malacosoma in the family Lasiocampidae. Twenty-six species have been described, six of which occur in North America and the rest in Eurasia. Some species are considered to have subspecies as well. They are often considered pests for their habit of defoliating trees. They are among the most social of all caterpillars and exhibit many noteworthy behaviors.

The eastern tent caterpillar is a species of moth in the family Lasiocampidae, the tent caterpillars or lappet moths. It is univoltine, producing one generation per year. It is a tent caterpillar, a social species that forms communal nests in the branches of trees. It is sometimes confused with the spongy moth and the fall webworm, and may be erroneously referred to as a bagworm, which is the common name applied to unrelated caterpillars in the family Psychidae. The moths oviposit almost exclusively on trees in the plant family Rosaceae, particularly cherry (Prunus) and apple (Malus). The caterpillars are hairy with areas of blue, white, black and orange. The blue and white colors are structural colors created by the selective filtering of light by microtubules that arise on the ballcuticle.