Squash Vine Borers

Identification

Adult squash vine borers are red and black moths that look like large wasps. Their larvae are chubby, white caterpillars found inside the base of squash vines.

Damage

The presence of borers is often noted as a rapid wilting of the plant. Look for hole in the stem tissue near ground level for confirmation.

Prevention

Wrap a strip of aluminum foil around the base of the plant soon after the first true leaves appear to protect the base of the plant from egg-laying females (more on this technique here).

Physical control

Cover plants with floating row cover soon after planting and leave in place until flowering begins. If borer hole is found before plant dies, slice open the stem, dig out the borer, and cover the cut with a mound of soil.

Chemical control

Inject Bacillus thuringiensis Kurstaki strain (Btk) into the borer hole with a needle-less syringe. You can also spray insecticidal soap on base of stem weekly to smother any eggs. Check local regulations (or your local Extension Office where applicable) to identify which products can be used in home gardens in your area. Follow label instructions carefully for safe and effective insecticide application and to ensure that edible crops are safe to harvest. Test insecticide on a few plants before widespread application.