Newspaper article Pittsburgh Post-Gazette (Pittsburgh, PA)

Preventive Steps Best Way to Fight Squash Vine Borers

Newspaper article Pittsburgh Post-Gazette (Pittsburgh, PA)

Preventive Steps Best Way to Fight Squash Vine Borers

Article excerpt

Q. Squash vine borers ruined my zucchinis this year. Can you recommend steps I can take to avoid this problem next year?

A. Squash vine borers are pests of summer and winter squash and pumpkins and, to a lesser extent, cucumbers and melons. They overwinter as pupae in the soil under host plants, and adults become active mid- to late June or early July. There is a single generation yearly in Pennsylvania.

Adult squash vine borers are clearwing moths that resemble wasps more than anything. Unlike most moths, they are active during the day. They have a 1- to 11/2-inch wingspan, with metallic green forewings. The rear wings are transparent, with black or brown margins and veins. The body is orange and black.

Adult female moths lay their eggs on the main stems and sometimes the leaf stalks (petioles) in July and August.

The oval eggs are reddish-brown and flat and usually laid singly or in small groups.

The small white larvae hatch in a week to 10 days and bore into the stem where they feed for about a month. The mature larva is a thick, white wrinkled worm with a brown head and is about 1 inch in length. They exit the stems and burrow into the soil to pupate.

The leaves on infested stems wilt when the borers' feeding destroys the plant's vascular system.

Once that occurs, the plant is unable to take up sufficient water to support the leaves. Upon close examination, you can see frass -- sawdust-like excrement -- coming from holes in the infested stems.

Prevention is the best course of action because squash vine borers cannot be controlled with insecticides once they get inside the stems.

Crop rotation is important because they overwinter in the soil under their host plants. Avoid growing susceptible crops in the same area from year to year.

Also, be sure to remove spent cucurbit crops at the end of the season to remove any larvae that may still be present. …

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