Insect Pests

Squash vine borer larvae are stocky white caterpillarsthat reach over 1 inch long when full grown. - Clemson University, USDA Cooperative Extension Slide Series, www.insectimages.org

The squash vine borers are serious enemies of squash and gourds but rarely attack cucumbers and melons. Named for its boring into stems, the borer’s tunneling often kills whole plants, especially if they attack the base. If you see sudden wilting of plants and sawdust-like waste coming from a hole in the stem, the borers are at work inside.

Borers spend the winter in the soil as larvae or enclosed in cocoons. Moths emerge in late spring and early summer and lay eggs on the stems of the plants, where young larvae can bore into the stems and begin feeding inside. Once inside, they are impossible to control.

Some gardeners have luck performing “surgery” by slitting infested vines lengthwise to remove borers, then covering the slit stem with soil to encourage it to root and renew the plant. It’s important to water regularly at this time.

Because the borers spend the winter in the soil, you can keep from rearing your own new enemies next year by turning the soil in late winter to expose the over-wintering pests to killing cold. Also destroy and remove vines that have been killed. Try to stay ahead of borers by planting as early as the weather allows, since the borers do not usually emerge until late spring or early summer.

Some squash and pumpkin varieties such as Butternut and Green-Striped Cushaw varieties are nearly immune to attack, but others such as Hubbard squash are very susceptible.