# Squash bug (Anasa tristis) > A common North American garden pest that sucks sap from squash and related plants, causing wilting and reduced yields. Source: https://insectscanner.com/species/squash-bug/ (updated 2026-10-10) ## Is it dangerous? **Non-toxic.** Squash bugs are not venomous and do not pose a medical threat. They can release a foul odor when crushed and may pinch if handled, causing minor, brief discomfort. Clean any skin contact and avoid crushing them on skin. **Pets:** Not dangerous to pets. Large numbers on plants are a garden concern but do not cause poisoning in cats or dogs. ## Quick facts - Scientific name: Anasa tristis - Also called: Common squash bug - Order: Hemiptera (True bugs) - Family: Coreidae (Leaf-footed bugs and squash bugs) - Size: 12-17 mm long - Colours: Brown, Gray, Black, Orange - Habitat: Gardens, agricultural fields and weedy edges where cucurbit plants grow; overwintering in leaf litter, compost piles, fence rows and buildings - Range: Widespread across North America; also reported in parts of Central America - Active: Spring to fall (most damaging mid-summer); active during daylight - Lifespan: Adults can live several months; they overwinter and reproduce the following year - Effect on plants: Garden pest - Pest: yes ## Overview Anasa tristis, the squash bug, is a true bug (family Coreidae) that feeds on plants in the cucurbit family (squash, pumpkin, cucumber, melon). Adults are dull, flattened, and somewhat shield-shaped; young nymphs are green with red heads and legs and turn gray as they mature. They can reach pest status in home gardens and small farms by reducing plant vigor and transmitting the bacterium that causes cucurbit yellow vine disease. Adults overwinter in leaf litter, field edges and nearby buildings, then emerge in spring to mate and lay rows of barrel-shaped eggs on the undersides of cucurbit leaves and stems. Populations build through late spring and summer when multiple generations may occur in warm regions. ## How to identify it Adults are 12-17 mm long, elongate and flattened with a gray-brown to dark brown body, often speckled, with orange-and-brown striped edges to the abdomen. They have long antennae and a fourth antennal segment often darker. Nymphs hatch as small, green, wingless immatures with red heads and legs; as they progress through instars they turn pale gray with darker legs and wing pads appear until the adult winged form is reached. Eggs are laid in neat, slightly angled rows, pale bronze to copper when fresh and darker with age. - Look for flattened, shield-like adults 12-17 mm long with gray-brown coloration and long antennae. - Find clusters of small, barrel-shaped eggs in neat rows on the undersides of cucurbit leaves. - Young nymphs are green with red heads and legs before turning pale gray and developing wing pads. - Damage: wilting patches on vines and stippled or sunken areas on fruit are typical signs of feeding. ## Lookalikes - **Leaf-footed bug** (Leptoglossus spp.): Leaf-footed bugs (Leptoglossus) are larger (often 18-25 mm), have expanded leaf-like hind tibiae and a distinct white zigzag band across the wings, while Anasa tristis lacks the leaf-like hind legs and has a more evenly brown-gray body. - **Horned squash bug** (Anasa armigera): Very similar and also feeds on cucurbits, but has small spines on the head and on the corners of the pronotum, which Anasa tristis lacks. ## Life cycle - **Egg:** Laid in clustered, slightly angled rows on the undersides of cucurbit leaves or along stems; coppery when new and darken before hatching. - **Nymph (immature):** Several instars: early nymphs are green with red heads and legs, later instars are pale gray and develop wing pads while actively feeding on plants. - **Adult:** Winged, dull brown-gray bugs about 12-17 mm long that mate and disperse; adults overwinter and lay eggs in spring. ## Diet and predators - Young eat: Sap from stems, leaf veins and developing fruit of cucurbit plants - Adults eat: Same as juveniles: plant sap from cucurbits; may also feed on related weeds - Predators of the young: Egg and nymph predators include spiders, ants, assassin bugs, and parasitic wasps (some hymenopterans attack eggs); birds also eat nymphs - Predators of adults: Generalist predators (birds, larger predatory insects) and some entomopathogenic fungi and diseases ## Effect on plants and gardens Feeds by sucking sap from stems, leaves and fruit of cucurbits (squash, pumpkin, zucchini, cucumber, melon). Feeding causes wilting, yellow spots, collapse of vines ('anasa wilt') and blemishes on fruit; heavy infestations reduce yield. ### How to get rid of it Remove and destroy egg clusters from leaf undersides every few days, and handpick nymphs and adults into soapy water. Lay boards near plants overnight and collect the bugs hiding underneath in the morning. Use floating row covers on young plants until flowering, clear crop debris and weeds after harvest to reduce overwintering sites, and rotate cucurbit plantings. If needed, insecticidal soap or other products labeled for squash bugs work best on young nymphs; follow label directions and avoid spraying open flowers visited by bees. ## Where and when to find it Look on the undersides of cucurbit leaves, along stems and on the soil surface nearby. Eggs are on leaf undersides in clusters; nymphs are on leaves and stems; adults hide in nearby leaf litter or structures when not feeding. - Best time: Best observed from late spring through summer during daylight hours; early morning or warm afternoons when bugs are active on plants. - Tips: Check leaf undersides for copper-colored egg clusters and green young nymphs. Wear gloves when handling to avoid their odor and drop them into soapy water to remove them. ## Fun facts - Squash bugs often cluster together, with groups of nymphs feeding side by side near where they hatched. - Nymphs change color dramatically as they grow, starting green with red legs and turning ash-gray. - Adults can overwinter in garden debris or buildings and reappear in spring, which is why sanitation helps control them. ## Frequently asked questions ### Do squash bugs bite? They are not known to bite people for food. If handled, they may pinch or release an unpleasant odor, but they do not deliver venom and bites are rare and minor. ### Why are squash bugs in my house? Adults may wander indoors in late summer or fall seeking sheltered overwintering sites such as wall voids, garages or leaf litter. They prefer outdoor hiding spots but sometimes enter buildings. ### How do I get rid of squash bugs in my garden? Use integrated methods: remove and destroy egg clusters by scraping leaves, handpick adults and nymphs into soapy water, remove crop debris and weeds where they hide, use row covers early in the season, and encourage predators. Chemical controls (targeting small nymphs) are a last resort—follow label directions. ### Are squash bugs harmful to my plants? Yes. Their sap-sucking weakens vines, causes wilting and can reduce yields. Heavy infestations can kill young plants or ruin fruit appearance. ### When are squash bugs most active? They are most active from late spring through summer, especially mid-summer when nymphs and adults feed heavily during daylight. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/143660), [Wikipedia](https://en.wikipedia.org/wiki/Anasa_tristis). 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.