Malacosoma disstria

Hübner

Forest Tent Caterpillar Moth

The forest (Malacosoma disstria) is a native North American lasiocampid moth known for its periodic . Unlike its the eastern tent caterpillar, it does not construct true silken tents; instead, larvae form silk mats on which they rest between feeding bouts. The is highly on deciduous trees and exhibits gregarious in early instars, becoming more solitary in later stages. Population cycles are regulated by natural enemies including , flies, and .

Malacosoma disstria by (c) Ken-ichi Ueda, some rights reserved (CC BY), uploaded by Ken-ichi Ueda. Used under a CC-BY license.

Malacosoma disstria var. anita by the Smithsonian. Used under a CC0 license.

Malacosoma disstria by Scott Tunnock, USDA Forest Service, Bugwood.org. Used under a CC BY 3.0 us license.

Pronunciation

How to pronounce Malacosoma disstria: /ˌmælɪkoʊˈsoʊmə ˈdɪstriə/

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Identification

Larvae distinguished from Malacosoma americanum (eastern tent caterpillar) by white keyhole-shaped markings (versus continuous white dorsal stripe in M. americanum) and lack of true silken tents—M. disstria forms only silk resting mats. distinguished from other Malacosoma by wing pattern and geographic distribution. From other by combination of range, larval markings, and nest structure.

Images

Habitat

Deciduous forests, woodlands, and urban areas with broadleaf trees. Found in riparian zones, forest edges, and suburban landscapes where trees occur.

Distribution

Transcontinental in North America. Documented from all Canadian provinces except Nunavut, and throughout the United States from the Atlantic to the Pacific, including southern states. Absent only from the far north and extreme southwestern deserts.

Seasonality

emerge and mate in June to July. hatch in early spring, with larval development occurring April through June in most of the range; timing varies latitudinally from April in southern U.S. to July in northern regions.

Diet

Highly on foliage of deciduous broadleaf trees. Southern prefer water oak (Quercus nigra) and sweetgum (Liquidambar styraciflua); northern populations prefer sugar maple (Acer saccharum) and aspen (Populus spp.). Also feeds on birch (Betula), cherry (Prunus), and other hardwoods.

Host Associations

Quercus nigra - preferred (southern )
Liquidambar styraciflua - preferred (southern )
Acer saccharum - preferred (northern )
Populus spp. - preferred (northern )
Betula spp. -
Prunus serotina -

Life Cycle

Overwinters as in dark brown, Styrofoam-like egg masses encircling small branches. Eggs hatch in spring when foliage emerges. Larvae pass through five to eight instars over four to seven weeks. Early instars are gregarious, forming silk mats on which they rest; later instars become solitary and wander more widely. occurs in silken cocoons on tree trunks, under bark, or on nearby structures. emerge, mate, and females lay eggs on branches. One per year.

Behavior

First-stage larvae exhibit behavioral with active and sluggish types; active individuals show directed toward light sources, though responses are inconsistent across days. Early instars are gregarious, forming communal silk resting mats; later instars disperse and feed more solitarily. Larvae do not construct the enclosed silken tents characteristic of M. americanum. Mass wandering occurs in late instars when food is depleted.

Ecological Role

Defoliator of deciduous forests; periodic can cause severe defoliation, though tree mortality is rare. Outbreaks may alter forest dynamics by promoting understory growth and shifting composition toward conifer dominance. Serves as for diverse complex including braconid wasps, tachinid flies, and sarcophagid flies. Microsporidian contribute to .

Human Relevance

Nuisance pest in urban and suburban areas due to defoliation of ornamental trees and mass cocoon formation on buildings, walls, and outdoor structures. Not economically impactful to forestry. Managed through mechanical removal of masses, sweeping of larvae, adhesive trunk bands, and microbial (Bacillus thuringiensis, spinosad, ).

Similar Taxa

Malacosoma americanumConstructs enclosed silken tents in branch crotches; larvae have continuous white stripe rather than keyhole markings; more densely hairy; oligophagous on Rosaceae.
Malacosoma californicumWestern ; larvae show more consistent active/sluggish behavioral than M. disstria.

More Details

Population Cycles

exhibit periodic cycles lasting several years, followed by decline due to natural enemies and resource depletion.

Behavioral Transition

Gregarious in early instars shifts to solitary behavior in fifth and sixth instars, possibly due to increased food requirements or reduced risk with size.