The squash vine borer (Melittia cucurbitae) tunnels in the vines of pumpkins and summer and winter squash; it rarely is found in cucumbers or melons and cannot complete its development except in squash or pumpkins.
The larva is white, thick-bodied, legless, and 1 inch long when full grown. The adult is a red and black, wasplike moth with clear wings and tends to sit on host plants and beans in the early morning. Reddish brown eggs are laid at the base of the stem just above or below the soil line.
The larva tunnels in the stems of squash, pumpkin, and other vine crops, causing plants to wilt and die in mid- to late season.
Squash vine borer adults emerge from cocoons in the ground in early summer. Eggs are laid at the base of susceptible plants. About seven days later, emerging larvae bore into the center of the stems to feed. The four to six weeks of feeding will causes the plant to wilt and die. The larvae pupate about 1 to 2 inches below the soil surface. In northern Illinois there is one generation per year, and pupae remain in the soil until the following growing season. In southern Illinois there may be a second generation each season.