Squash Bug

DESCRIPTION AND BIOLOGY: Squash bugs are one of the primary pests of cucurbits in the United States. Adults are typically 10 to 30 mm long, dark gray, brown or black in color with orange or brown markings on the sides of the abdomen (Fig. 1). Overwintering adults emerge from the soil, ground litter, wood piles or buildings in the spring. After feeding and mating, females deposit egg masses on the underside of leaves. Newly laid eggs are typically light pale in color, become coppery, then darker as they develop. Egg masses are commonly laid in diamond or V-shaped patterns along leaf veins (Fig 2). Nymphs are 2.5 to 10 mm long, light green upon hatching and light to dark gray with each successive molt (Fig. 3). Nymphs have black legs and antennae. There are five nymphal instars with an average development time of 33 days. The last two instars have a more distinct thorax and wing pads. Nymphs aggregate and feed close to their parent egg mass, on the underside of leaves, until later stages of wilt set in on the leaf (Fig. 3). Squash bug nymphs and adults are cryptic, frequently hiding in the shaded parts of plants, under plastic mulches, in thick weed beds, or in wilted fruit and foliage. Squash bugs can complete their egg to adult life cycle in four to six weeks. Fig. 1. Adult female squash bug laying eggs on the underside of a pumpkin leaf. Fig. 2. Squash bug egg mass in a common v-shaped pattern