Other Common Names
Eastern Tent Caterpillar (larva)
Synonyms and other taxonomic changes
Malacosoma americana (Fabricius, 1793)
Bombyx americana Fabricius, 1793
one of 6 species in this genus in North America common
Caterpillar length to 57 mm (2¼ in) (2)
Adult: body and wings warm fawn brown; forewing with white AM and PM lines; median area sometimes white (1)
wings of male are darker and more brownish; wings of female are paler and more yellowish
Larva: distinguished by a solid cream/white line along the dorsum (middle of the back). Sides of the body are marked with blue, black, orange and white. Dark face.
Eastern and central US to the Rockies (2)
and Canada from Nova Scotia to Alberta
Tents appear in early spring, and caterpillars are seen until early summer (3)
Moths fly from late May to June (1)
larvae feed on leaves of many trees and shrubs but particularly members of the rose family such as apple, cherry, and crabapple (1)
Female deposits egg mass on twig where it overwinters (2)
Larvae emerge in spring and begin building their tent which they continue to expand as they grow.
Fully grown caterpillars eventually disperse and find a place to pupate.
1.group of larvae 2.Cocoon 3.Pupa 4.Adult female 5.Adult male
one generation per year; overwinters as an egg
A good overview of larval habits (shelter building, feeding, thermoregulation, anti-predator defense, trail making and recruitment) appears on this page
by Terrence Fitzgerald.
The gender of Malacosoma
is neuter, so adjectivic species names ending -a are considered wrong spellings. (4)
forewing has dark AM and PM lines. The median area is often darker than the remainder of the forewing.
is slightly smaller but otherwise similar and probably indistinguishable from M. americanum
in areas where their ranges overlap.
of all 3 species at CBIF
of Forest Tent Caterpillar
) has a broken dorsal line forming keyhole or footprint shapes along its back, and generally more blue on its body, including the face. Larvae form silken mats where they congregate, not tents.
Fabricius, 1793. Ent. Syst. 3(1): 433
Stehr, F.W. & E.F. Cook 1968. A revision of the genus Malacosoma
Hübner in North America (Lepidoptera: Lasiocampidae): systematics, biology. immatures, and parasites. Bulletin of the United States National Museum
. 276: 1-321. (4)