The summer growing season is here and the questions are pouring in about squash vine borers. If you are growing squash in your vegetable garden, I am sure you are familiar with this formidable pest. Hate is the emotion often expressed when describing this key pest of squash, pumpkin and gourds. I know gardeners who no longer plant squash varieties because of the squash vine borer.

Symptoms from the squash vine borer usually appear in the summer when the entire plant starts to suddenly wilt. The squash vine borer feeds on the lower stem preventing water and nutrients from reaching the upper parts of the plants. This damage can weaken the plant and cause it to die. Sawdust-like frass (excrement) can be found near the base of the plant which signals squash vine borer activity.

The adult squash vine borer looks like a wasp. This moth has clear hind wings with a brown border of scales. The abdomen of the moth has black and orange stripes. The moth is very active during the day. They will land on leaves and stems and lay single eggs. The eggs hatch in seven to ten days. The larvae immediately start to bore into the stem of the plant. Once they finish feeding, they exit the stem to pupate in the soil which gives rise to a second generation of larvae during August.

It is best to control the squash vine borer before they enter the stem. Once inside the vine, insecticidal control is deemed ineffective. Destroy vines soon after harvest to kill any larvae that may be present inside the stem. The larvae can be physically removed with tweezers after splitting the vine with a knife. The area above the point of injury can be covered with soil to promote new root growth. Scout for small, brownish eggs on the stem or leaves and hand-pick or destroy them.

There are a few insecticides that can be used for squash borer control in the garden. They include carbaryl (Sevin), esfenvalerate (Ortho Bug B Gon Insect Killer), spinosad (Monterey Garden Insect Spray) and permethrin (Bonide Total Pest Control Concentrate). Please follow the label directions.

Squash vine borers can be devastating to your crop and difficult to control. They’re here! Now is the time to examine your squash plants for signs of borers to minimize damage. Good luck in controlling this pest!

Until next time happy gardening!