Squash Vine Borer

The squash vine borer is a clearwing moth native to North America that flies during the day and is frequently mistaken for a wasp due to its orange-scaled hind legs and buzzing flight. It is a serious pest of cucurbit crops, and a single infestation can kill an entire squash, zucchini, pumpkin, or acorn squash plant within a few weeks. Gardeners in Zone 6b typically deal with one generation per year, with adults emerging in late June through July.

Females lay flat, reddish-brown eggs singly at the base of leaf stalks and main stems. Larvae hatch and immediately bore into plant tissue, feeding internally and cutting off water and nutrient flow. The first sign is often greenish-yellow frass pushed out of a small entry hole near the stem base, followed by sudden wilting. By the time collapse is visible, the damage inside is already severe. Because larvae are protected inside the stem, surface-applied insecticides have limited effectiveness once boring has begun, making early detection and prevention the most reliable approach.

A destructive larval pest that bores into and feeds inside the stems of cucurbit crops, often killing plants outright.