Squash Vine Borer

Q.  I have vine borers in my squash. Can I control them with insecticide?

A.  No. Vine borers cannot be controlled effectively with insecticides once they have infested the plants. Dispose of the infested plants to reduce potential damage in following seasons. Apply insecticide before vines are infested.

Q. Each year my squash plants wilt and die about the time they start producing. Some have a yellowish or greenish sawdust­like material all over the vines. What could possibly be wrong?

A.  Your problem is probably squash vine borer, and if it is, the white, grub­like larvae can be found within the stem of the plant by cutting it open. The larvae hatch from eggs laid by bright­colored, wasp­like moths on the foliage or stems. The eggs hatch, and the larvae travel down the plant to the stem and literally “core it out.” To prevent this problem, begin control measures about the time the plants start to bloom by applying an insecticide to the base of the plant. Once grubs are inside the stem, they are almost impossible to control. During the fall growing season, begin treatment shortly after plant emergence.

More information about squash vine borers

Squash vine borers are clear­winged moths that lay eggs near the base of squash vines. When the larvae enter a stem, little can be done. Chemical control is possible only if an insecticide is present when young larvae hatch from the egg prior to entering the plant.

See our summer squash fact sheet for more information and visit our summer squash gardening page for details.

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