Sunday, November 21, 2010

Squash Vine Borers are Active in Gardens

Squash vine borers are the most common and can be the most damaging pests of squash. The larvae tunnel into the stems of squash and other plants, including melons and cucumbers. This causes the stems to wilt and die. The adult moths resemble a wasp, with a red abdomen surrounded with black bands at each segment; their front wings are covered with metallic brown scales and their back wings are clear with a brown band. Adult females lay eggs on the leaves and stems of primarily squash. The larvae hatch and begin burrowing into host plant stems. The larvae are white in color with a brown head and they grow to be an inch in length. The larvae will produce sawdust like frass near the base of the plant as they tunnel and then climb from the stem to pupate in the soil.

Some Control Suggestions:

Some Non-Chemical Controls:

Keep natural enemies in the garden such as parasitic wasps that will attack squash vine borer eggs and larvae. Also adult ground beetles (Family Carabidae) will attack squash vine borer larvae.
When wilting is noticed, a sharp knife can be used to cut a slit into the stem so the larva can be removed. New roots may grow along the cut stem, allowing the plant to survive. Split vines should be covered with soil immediately after the larvae have been removed.
Also remove vines soon after harvest to destroy any larvae that still might be inside the stems.

Some Chemical Controls:

Some chemical suggestions include using such active ingredients as pyrethrins, permethrin, or carbaryl. Apply the dusts or sprays to the base of the plant.

Photo of a southwestern squash vine borer, Melittia calabaza (Lepidoptera: Sessidae), larva. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

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