# Eastern tent caterpillar moth (Malacosoma americana) > A common spring caterpillar that builds silk colonies in tree forks, defoliates cherry and other fruit trees but rarely causes long-term tree death. Source: https://insectscanner.com/species/eastern-tent-caterpillar-moth/ (updated 2026-10-10) ## Is it dangerous? **Irritating hairs.** Eastern tent caterpillars are not venomous and do not bite or sting, but their hairs can cause mild skin irritation or a rash in sensitive people after handling. Remove hairs from skin with adhesive tape and wash the area with soap and water. Seek medical advice for severe allergic reactions. **Pets:** Pets that chew or roll in masses of caterpillars may get mild skin irritation or vomiting; serious poisoning is rare. Prevent pets from eating large numbers and contact a veterinarian if symptoms appear. Horses are a special case: pregnant mares that swallow the caterpillars can lose their foals (mare reproductive loss syndrome), so keep horses away from heavily infested wild cherry trees in spring. ## Quick facts - Scientific name: Malacosoma americana - Also called: Eastern tent moth, Apple tent caterpillar - Order: Lepidoptera (Butterflies and moths) - Family: Lasiocampidae (Tent caterpillars and lappet moths) - Size: 2.5-4 cm wingspan - Colours: Black, Cream/white, Blue (bluish spots), Chestnut orange - Habitat: Deciduous woodlands, orchards, shade and ornamental trees, hedgerows and suburban yards where host trees occur. - Range: Eastern and central North America, from the Gulf states north into southern Canada and west to parts of the Midwest. - Active: Larvae: early spring (shortly after trees leaf out). Adults: late spring to early summer. Larvae are active during daylight and at night when feeding. - Lifespan: Adults live about 1-2 weeks; larval stage lasts several weeks in spring; full generation is annual. - Effect on plants: Defoliator - Pest: yes ## Overview Malacosoma americana is a North American moth whose larval stage (the eastern tent caterpillar) is best known for conspicuous communal silk tents built in the forks of deciduous trees. The species is widespread across eastern North America. Larvae feed gregariously on the leaves of wild and cultivated trees in spring, then pupate and emerge as small brown moths. Outbreaks can cause noticeable defoliation of fruit and shade trees but trees usually recover. ## How to identify it Larvae: up to about 5-6 cm long when fully grown, hairy and black with a broad, pale (cream to white) dorsal stripe edged with black. Along the sides they carry rows of bluish and chestnut-orange spots and many fine hairs. They move and feed in groups and sit together in silken communal tents in branch crotches. Pupae: brown, inside whitish to yellowish silk cocoons spun in sheltered spots such as bark crevices, fences or under eaves. Adult moth: stout, furry-bodied, with a wingspan around 2.5-4 cm; forewings are reddish-brown to chestnut with two pale, parallel diagonal lines, hindwings paler. - Look for white silk tents in the forks of deciduous trees in spring where caterpillars cluster. - Caterpillars are black with a distinct broad white/cream dorsal stripe, bluish lateral spots and chestnut-orange markings. - Egg masses are glossy, brownish bands wrapped around small twigs from the previous year. - Adult moths are stout, furry, reddish-brown with two pale diagonal lines across each forewing; wingspan about 2.5-4 cm. ## Lookalikes - **Forest tent caterpillar** (Malacosoma disstria): Forest tent caterpillar does not build above-branch tents; larvae have a series of keyhole-shaped pale spots along the back instead of a single continuous pale dorsal stripe. - **Fall webworm** (Hyphantria cunea): Fall webworm builds large loose webs that enclose foliage at branch ends in summer/fall, and larvae are generally paler and fuzzier with differently arranged spots. ## Life cycle - **Egg:** Eggs are laid in masses (bands) around twigs in mid to late summer; masses are covered with a shiny, brownish varnish and overwinter on branches. - **Larva (caterpillar):** Eggs hatch in early spring when buds open. Larvae are social, build communal silken tents in branch crotches, and feed gregariously on new leaves for several weeks. - **Pupa (cocoon):** Mature caterpillars leave the tree and spin whitish to yellowish silk cocoons in sheltered locations such as bark crevices, fences and buildings; the pupal stage lasts about 3 weeks. - **Adult (moth):** Adult moths are short-lived, mate, and females lay egg masses on twigs before dying; one generation per year. ## Diet and predators - Young eat: Leaves of cherry, apple, plum, hawthorn, and other deciduous trees and shrubs. - Adults eat: Adults have reduced mouthparts and do not feed significantly; their energy is spent on reproduction. - Predators of the young: Birds, predatory insects, parasitic wasps and flies, and small mammals; diseases and viral pathogens also reduce populations during outbreaks. - Predators of adults: Bats, night-flying insectivorous birds, and parasitoids. ## Effect on plants and gardens Larvae feed on leaves of cherry, apple, crabapple, plum, wild cherry, hawthorn and various hardwoods. Heavy spring defoliation can weaken young or repeatedly attacked trees, but healthy mature trees usually refoliate the same season. ### How to get rid of it Remove and destroy visible silk tents and egg masses by hand in early morning or evening when larvae are inside the tent. Prune out and destroy infested branches. For large outbreaks use regulated insecticidal options like Bacillus thuringiensis kurstaki (Bt) applied while larvae are young and actively feeding. Keep natural predators (birds, parasitic wasps) and avoid broad-spectrum insecticides when possible. ## Where and when to find it Look for tents in the forks of cherry, apple, plum and other deciduous trees. Eggs are visible as varnished bands on twigs in late summer to winter; caterpillars and tents appear in early spring. - Best time: Best observed in spring, shortly after leaves emerge (often March to May depending on latitude). Daytime is good for photographing tents and basking larvae. - Tips: Approach tents slowly — caterpillars often withdraw into the silk. Use a long lens for close-ups and wear gloves if handling branches; remove egg masses in winter for prevention. ## Fun facts - Eastern tent caterpillars are one of the first conspicuous caterpillars in spring because their eggs overwinter on twigs and hatch as buds open. - Tents serve as communal 'home base' where caterpillars bask to raise body temperature and return between feeding bouts. - Populations show cyclical outbreak patterns: years with heavy defoliation are often followed by years of low numbers due to predators and disease. ## Frequently asked questions ### Are eastern tent caterpillars dangerous? Only mildly. They are not venomous or aggressive, and they do not bite or sting, but their hairs can cause mild skin irritation in some people if handled. Pregnant mares that eat them can lose their foals, so horse owners should take care. ### Do eastern tent caterpillars bite? No. Caterpillars feed on leaves; they do not bite people. Any discomfort from contact is caused by irritating hairs, not a bite. ### Why is there a tent in my tree? The silk structure is a communal tent built by eastern tent caterpillar larvae as shelter and a place to warm up between feeding trips. ### Will they kill my fruit tree? Occasional spring defoliation usually does not kill healthy mature trees; repeated heavy defoliation over several years can weaken young or stressed trees and reduce fruit yield. ### How do I get rid of eastern tent caterpillars? Prune out and destroy egg masses in winter and tents/infested branches in spring. For larger outbreaks, apply Bacillus thuringiensis (Bt) when larvae are small, or consult local extension services for approved controls. ### When will the tents disappear? Tents are used only while larvae are feeding in spring; after pupation (a few weeks to a month), tents are abandoned and will weather away or be removed during pruning. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/211100), [Wikipedia](https://en.wikipedia.org/wiki/Eastern_tent_caterpillar). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.