Stop Squash Vine Borers: Prevention and Control

Squash vine borers are insidious: you often don't see them until the plant wilts. The white, black-headed larvae (up to 1 inch) tunnel inside stems, leaving sawdust-like frass at entry holes. A single vine can host 100 borers. Adults are gray moths with furry red legs and clear hind wings, resembling wasps.

Control Strategies

Sanitation: Remove and trash infested vines before season's end to prevent larvae from entering soil.

Soil tillage: Till in spring or fall to disrupt cocoons.

Trap crop: Plant 'Hubbard' squash — a borer favorite. When infested, remove and destroy the whole vine.

Crop rotation: Move squash to a new spot each year so emerging moths can't find host plants.

Stem barriers: Wrap stems with nylon cloth or burlap to prevent egg-laying and boring.

Surgical removal: If caught early, slit stem vertically at frass hole, remove borer, and cover wound with soil.

Insecticides (preventive): Apply insecticidal soap or carbaryl weekly for 3-6 weeks in June/July when moths are active. Since borers live inside stems, sprays must target eggs and young larvae before entry.