The squash vine borer is a native of this hemisphere, occurring east of the Rocky Mountains from Canada to Brazil.
It attacks squashes and pumpkins and occasionally gourds, melons and cucumbers.
Squash Borer Appearance and Habits
The insect winters as a larva or pupa inside a silk-lined dark cocoon an inch or two below soil level. The adult is a wasplike moth, with copper-green forewings and orange and black abdomen, appearing in June in the Middle Atlantic States. It lays 150-200 eggs, singly, on the stem, especially at the base of the main stem, leaf stalks, blossoms. The young borers hatch in about a week, tunneling into the stem to feed. Usually the first sign of their presence is a sudden wilting of the vine, at which time close examination discloses masses of greenish-yellow excrement protruding from holes in the stem. The borer, a white, wrinkled caterpillar about 1 in. long, can be seen by slitting the stem with a knife.
How to Manage Squash Borers
Baby blue and butternut squash can resist the borer to some degree.
If a change in location is possible, do not grow squashes two years in succession on the same ground. If the same area must be used, spade or plow it in the fall to expose the cocoons. Pull up and burn vines immediately after harvest.
If a vine starts to wilt, kill the borer with a knife and heap earth over the stem joints to start new roots.
Make a second planting of summer squash to mature after the first borer brood has disappeared.