Randy Nelson Clay County Extension

Squash vine borer

Start monitoring for squash vine borer if you are growing summer squash, winter squash, or pumpkin in your garden. Squash vine borer is a potentially devastating pest as the larvae bore into the stem, causing the plant to wilt and eventually die. The best management is well timed insecticide treatments when adults are active and laying eggs.

The squash vine borer is a common clearwing moth found in home gardens. The adult squash vine borer begins to emerge from cocoons in the ground in late June or early July. The moth flies during the day and resembles a wasp. It is about one half inch long with an orange abdomen with black dots. The first pair of wings is an iridescent green while the back pair of wings (which may not always be seen plainly) is clear. The larvae are white or cream-colored with brown heads. The larvae grow to almost one inch in length.

There are a couple of methods for detecting them in your garden. Watch for them flying around while you are in your garden or try placing yellow containers (like pans or pails) half filled with soapy water. The moths are attracted to yellow and when they fly to the container they will fall in. Check containers daily for their presence.

As soon as you spot one squash vine borer, start treatment. There are a variety of insecticides that can be applied. If you do not see any but have a history of these pests in your garden, begin treatment by late June or early July. Insecticide active ingredients effective against squash vine borer include carbaryl, permethrin, bifenthrin, and esfenvalerate. Source: Jeffrey Hahn, Extension Entomologist (retired). More information about squash vine borer can be found at: http://z.umn.edu/squashborer

If you have questions about squash vine borer please call me at the University of Minnesota Extension office, Clay County at 218-299-7338 or email me at nels1657@umn.edu. Check out our website at https://local.extension.umn.edu/local/clay

The University of Minnesota, including the University of Minnesota Extension is an equal opportunity educator and employer.