Pest description and crop damage The adult squash bug is flat-backed, brownish black, and measures about 0.62 inch long. Eggs are elliptical and yellowish-brown turning dark brown with age. The nymphs have a green abdomen with crimson head, thorax, antennae, and legs which soon darken to reddish brown. Older nymphs are grayish white with black legs and antennae. Nymphs range from 0.19 to 0.5 inch long. Squash bugs feed primarily on squash and pumpkin. Adults and nymphs suck plant sap from the leaves and stems, causing wilting and death. Damage tends to be localized.
Biology and life history Squash bugs overwinter in protected places as unmated adults. They appear rather slowly in the spring. Adults mate and begin laying clusters of eggs about the time the squash vines begin to spread. Eggs are laid in clusters of a dozen or more on the leaves. They hatch in about 10 days into nymphs. Nymphs go through five molts before becoming adults in 4 to 6 weeks. There is only one generation per year.