# Spongy moth (Lymantria dispar) > A widespread tree-defoliating moth whose hairy caterpillars eat the leaves of many hardwood and conifer species and can cause large-scale defoliation. Source: https://insectscanner.com/species/spongy-moth/ (updated 2026-10-10) ## Is it dangerous? **Irritating hairs.** Caterpillar hairs and scales can cause skin irritation or an itchy rash (contact dermatitis) in sensitive people; inhalation of large numbers of hairs or scales may irritate the respiratory tract. Treat skin reactions by removing hairs with tape, washing with soap and water, and applying topical anti-itch treatments or seeking medical advice for severe reactions. **Pets:** Caterpillars may cause mouth or throat irritation if eaten by pets; monitor animals that attempt to eat caterpillars and contact a veterinarian for significant signs such as drooling, vomiting, or respiratory signs. ## Quick facts - Scientific name: Lymantria dispar - Also called: Gypsy moth - Order: Lepidoptera (Butterflies and moths) - Family: Erebidae (Tussock moths and relatives) - Size: Male wingspan 35-50 mm; female wingspan 50-75 mm - Colours: Brown, Cream, Black, Blue (larval spots), Red (larval spots) - Habitat: Forests, woodlands, parks and urban areas where host trees are present - Range: Native to Europe, parts of Asia and North Africa; established as an invasive species in eastern North America, with isolated introductions elsewhere - Active: Caterpillars active in spring and early summer; adults emerge mid to late summer depending on climate - Lifespan: Adults live about 1-2 weeks; the entire life cycle is annual (one generation per year) in most of its range - Effect on plants: Forest and ornamental pest - Pest: yes ## Overview Lymantria dispar is a species of tussock moth known for outbreaks in forests and urban trees. The caterpillars are the damaging stage, feeding on dozens to hundreds of tree and shrub species; repeated heavy defoliation can weaken trees and increase susceptibility to disease and other pests. The species is native to parts of Europe, Asia and North Africa and has been introduced to North America, where it is an important invasive pest. Adults are short-lived; females in some populations are flightless or poor fliers while males fly and seek mates. Populations undergo cyclical outbreaks where caterpillar numbers rise dramatically for a few years then collapse, often due to starvation, disease or predators. Management focuses on monitoring, targeted biological or chemical controls, and preventing spread of egg masses on vehicles and outdoor materials. ## How to identify it Adult males are brownish with feathery antennae and a wingspan around 35-50 mm; females are larger (up to 50-75 mm wingspan) and paler, often creamy white with darker markings, and in many populations the females have reduced flight ability. Caterpillars (larvae) are hairy, 35-75 mm long when mature, and have a distinctive line of five pairs of blue dorsal spots followed by six pairs of red dorsal spots along the back. Egg masses are tan to buff, spongy in appearance, and 40-70 mm long, typically glued to bark, firewood, vehicles, outdoor furniture and other surfaces. - Caterpillars with five pairs of blue dorsal spots followed by six pairs of red dorsal spots. - Spongy, tan egg masses 40-70 mm long attached to bark, wood, vehicles or outdoor objects. - Adult females are white or cream with dark markings and often poor fliers; males are brown and fly readily. ## Lookalikes - **Brown-tail moth** (Euproctis chrysorrhoea): Brown-tail caterpillars are dark brown with white tufts along the sides and two orange-red spots near the rear, not paired blue and red spots; their hairs are much more irritating to skin. - **Forest tent caterpillar** (Malacosoma disstria): Forest tent caterpillar has a keyhole-shaped dorsal series of spots rather than the blue/red paired spots of spongy moth; forest tent caterpillar eggs are laid in hard bands around twigs rather than in spongy masses. ## Life cycle - **Egg:** Egg masses are laid in late summer on bark, rocks or man-made objects; eggs overwinter and hatch in spring. - **Larva (caterpillar):** Caterpillars feed gregariously at first then disperse, consuming leaves for several weeks; this is the primary damaging stage. - **Pupa:** Caterpillars pupate in sheltered locations (bark crevices, leaf litter or man-made structures) for 1-3 weeks before emerging as adults. - **Adult moth:** Adults mate and females lay egg masses; adults do not feed and live briefly to reproduce. ## Diet and predators - Young eat: Leaves of many broadleaf trees and some conifers (oaks, birch, poplar, willow, maples and others) - Adults eat: Do not feed (adults have reduced mouthparts and short lifespans) - Predators of the young: Birds, small mammals, predatory insects, parasitoid wasps and flies, and disease (viral and fungal pathogens) - Predators of adults: Bats, nocturnal birds and some insectivores; eggs may be eaten by small mammals and invertebrates ## Effect on plants and gardens Polyphagous: larvae feed on many deciduous trees (oaks, birch, poplar, willow, maples) and some conifers; heavy or repeated defoliation can reduce growth, cause top dieback and increase tree mortality especially in stressed trees. ### How to get rid of it Monitor with pheromone traps and visual checks for egg masses in fall-winter. For small infestations remove and destroy egg masses, handpick caterpillars collected under burlap bands, or apply biological controls such as Bacillus thuringiensis var. kurstaki (B.t.k.) or the fungal pathogen Entomophaga maimaiga when timing matches larval hatching. For larger outbreaks consult local forestry or pest control authorities before using broad-spectrum insecticides. Prevent spread by inspecting and removing egg masses from vehicles, firewood and outdoor equipment. ## Where and when to find it Look for egg masses on tree trunks, under bark flaps, on rocks, fence posts, firewood and outdoor furniture in fall through spring; caterpillars are easiest to find on host tree foliage in spring and early summer. - Best time: Best observed as caterpillars in spring and early summer; adults appear mid to late summer. Daytime for caterpillars, nighttime or light sources for adults. - Tips: Use binoculars or a long lens for canopy searches. In winter search trunks and sheltered surfaces for tan, spongy egg masses. Wear gloves when handling caterpillars or egg masses to avoid skin irritation. ## Fun facts - The common name 'spongy moth' refers to the sponge-like texture of the female's egg masses. - Outbreaks can last several years and cause visible 'canopy browning' across large forested areas. - The North American population traces back to moths that escaped near Boston in the late 1860s, brought over by an amateur scientist hoping to breed silk moths. ## Frequently asked questions ### Are spongy moth caterpillars dangerous? They are not venomous, but their hairs can cause itchy rashes or mild allergic reactions in sensitive people; avoid handling and wash skin if contact occurs. ### Do spongy moths bite or sting? No. Adults and caterpillars do not bite or sting, though caterpillar hairs can irritate skin. ### Why are spongy moths in my house? Egg masses and pupae can be accidentally carried on firewood, outdoor furniture, vehicles or building surfaces; adults may also be attracted to lights but do not live long indoors. ### How do I get rid of spongy moths or their egg masses? Remove and destroy egg masses by scraping into a sealed bag and freezing or soaking in soapy water. During larval stage use targeted biological controls (B.t.k.) or consult local authorities for approved insecticides during outbreaks. ### Where do spongy moths live? They live where host trees are present: forests, woodlots, parks and suburban areas. Native ranges include Europe and parts of Asia; they are established as an invasive species in eastern North America. ### How can I prevent spreading spongy moths? Inspect and remove egg masses from outdoor items, avoid moving firewood, and check vehicles and trailers when traveling from infested areas. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/47802), [Wikipedia](https://en.wikipedia.org/wiki/Lymantria_dispar). 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.