Squash bugs: how to get rid of them

Last updated: October 2026

Squash bugs (Anasa tristis) are best controlled early: scout from planting, crush the bronze egg clusters on leaf undersides, handpick adults or trap them under boards, and cover young plants until bloom.^3,4 Clear crop debris after harvest to remove overwintering sites.⁴ Sprays such as insecticidal soap or oils work mainly on small nymphs, so time them to egg hatch and follow the product label.^1,4

How do you identify squash bugs and their eggs?

Squash bugs (Anasa tristis) are sap-feeding true bugs in the leaf-footed bug family, Coreidae.⁴ Adults are flat, about 5/8 inch long, gray to brownish black, with orange and brown stripes along the edges of the abdomen.⁴ A dense covering of fine hairs makes them look almost black.¹ Both adults and nymphs give off a foul odor when disturbed, which is why they are sometimes called stink bugs, but true stink bugs belong to a different family.⁴

The eggs are the easiest stage to find and the best one to destroy. They are oval, about 1/16 inch long, and laid in clusters on the undersides of leaves, usually between the leaf veins.⁴ Fresh eggs are pale and darken to a shiny coppery or brick-red brown.^3,4 A mass averages about 18 eggs and can hold more than 40.³ Newly hatched nymphs have red legs and heads with greenish bodies, and older nymphs turn gray with black legs.^3,4 Young nymphs are strongly gregarious and feed in groups.²

In North America overwintered squash bugs reach cucurbits in late spring to early summer (April to May in Utah, early to mid-June in New York), lay eggs through midsummer, and the new generation of adults appears from late June into August before seeking winter shelter^4,5,6. In the Southern Hemisphere the same sequence follows the warm season, with egg-laying from about late spring in November through midsummer.

What damage do squash bugs cause?

Adults and nymphs pierce leaves, vines and fruit and suck the sap.⁴ Leaves first show yellow spots that turn brown, and heavy feeding turns whole leaves black and crisp.⁴ Small plants can be killed outright, while larger plants lose runners.¹ Feeding on fruit leaves scars and sunken areas that cut quality and increase rot in storage.⁴ In one study cited in a 2016 review, untreated summer squash invaded at flowering and fruit set lost more than half its yield.³

The sudden collapse of vines is often called anasa wilt.² It was once blamed on a toxic saliva, but no salivary toxin has been confirmed, and the wilting is now explained mainly by disruption of the water-conducting xylem where the bugs feed.^3,4 This wilt resembles bacterial wilt, a disease spread by cucumber beetles, so check vines and leaf undersides for the bugs before deciding what you are dealing with.¹

Squash bugs also carry the bacterium that causes cucurbit yellow vine disease, and overwintering adults hold it inside their bodies until spring.^2,6 Losses from the disease range from 5% to 100%, no resistant cucurbit varieties are available, and yellowing of the leaves and vines separates it from bacterial wilt.⁶

When do squash bugs appear in the garden?

Squash bugs spend the winter as unmated adults under plant debris, in compost piles, around building foundations and in woodpiles.^2,4 In late spring to early summer they fly to young cucurbit plants to feed, mate and lay eggs.⁴ In Utah, overwintered adults typically emerge in April in the south and in May in the north, and in New York they usually emerge in early to mid-June.^4,6

Egg-laying continues from late spring through midsummer, so eggs, nymphs and adults overlap.^4,5 There is one generation a year in northern areas and two to three in warmer regions.² Infestations tend to build about the time plants reach 2 to 3 feet across, and numbers are highest during bloom and fruit set.^2,4 Warm winters favor adult survival and larger populations the following year.⁴

How do you get rid of squash bugs naturally?

Cultural and mechanical controls are the first line of defense, and they work best when started early.⁴ Each adult removed in spring can prevent several hundred offspring later in the season.⁴

• Scout at least once a week from seedling emergence or transplanting, checking leaf undersides for eggs and the plant base for adults.^1,4
• Handpick adults and nymphs and crush egg clusters every 2 to 3 days early in the season.⁴
• Drop bugs into soapy water, and lift eggs off leaves with the sticky side of duct or packing tape.⁵
• Lay boards, shingles or heavy cardboard beside the rows; squash bugs shelter under them at night and can be destroyed in the morning.^2,4
• Cover plants with floating row covers until they flower, then remove the covers so bees can pollinate.^4,5
• Remove vines, old fruit and debris right after harvest, and rotate cucurbits to a new spot.⁴
• Remove wilted plants and check the plants next to them for squash bugs.⁴

Do row covers, trap crops and natural enemies help?

Row covers delay colonization, but bugs move in quickly once covers come off for pollination.² Straw and other mulches can harbor squash bugs, so weigh their benefits against that risk.^3,4

Trap crops use the bug's preferences. Squash and pumpkin are preferred hosts and can protect melons and cucumbers planted nearby.^2,3 Hubbard squash on plot edges can help reduce cucurbit yellow vine disease in the main planting.⁶ Destroy the bugs on the trap crop before their eggs hatch.⁴

Natural enemies add real pressure. The tachinid fly Trichopoda pennipes lays eggs on older nymphs and adults, and about 20% of squash bugs collected in Connecticut in late summer were parasitized.^2,3 Tiny wasps parasitize the eggs, with up to 30% egg parasitism reported in Florida.² Avoiding broad-spectrum insecticides and growing flowering plants that feed these parasitoids helps preserve them.⁴

What organic pesticides work on squash bugs?

Target the nymphs. Adult squash bugs are unusually hard to kill and prone to developing resistance, while young nymphs are much more susceptible.^2,4 Utah State University uses an average of one egg cluster per plant as the threshold for treating.⁴

UC IPM lists pyrethrins, insecticidal soaps and certain oils as options acceptable in organic production.¹ Soaps and narrow-range oils need thorough coverage and control small nymphs but are not as effective on older nymphs or adults.¹ Pyrethrins and azadirachtin, the active compound in neem products, can suppress nymphs, but under heavy pressure they have not given effective or consistent control in the field.³ Spinosad has been evaluated and shown to be not very effective against squash bug.³

Protect pollinators. Spray in the early morning or evening, avoid spraying open blossoms during the day, and choose materials with little residual activity when flowers are present.^2,4,5 Cover the tops and undersides of leaves, fruits and vines, ideally before the canopy closes.⁴ Whatever you use, follow the product label.