Squash bug

Check the underside of leaves for clusters of squash bug eggs and be sure to destroy them.

If you grow vegetables in the cucurbit family, such as squash, pumpkin and cucumber, your garden has likely been visited by squash bugs.

A member of the Hemiptera order, these insects pierce the leaves to get to the juicy plant sap. Their feeding creates yellow specks on the leaves, which eventually turn brown, causing the plant to wilt. In addition, they can inject a toxin in the vines, leading the runners to turn black. Finally, they have been known to attack the fruit. Small young plants are most vulnerable.

Casey Leigh

Casey Leigh, WSU Master Gardener

Fortunately, if you act early, you can prevent an infestation that can destroy your hard work of planting and nurturing your crop.

The first step in the spring is to check the adults’ hiding places and destroy any squash bugs you uncover. They are about 3/4-inch long with wings, and a flat back. Their coloring is usually dark brown, but could have gray or light brown markings. Look for the orange-brown stripes on the sides of the abdomen, as well as the undersides. You will find them in garden debris left over from the fall, near buildings, hiding in your perennials and under boards or other wood in the garden.

To “trap” them, you can lay wooden boards in strategic spots and check under them each morning. Hand pick and kill any you find. Keep in mind that squash bugs fly, so be quick!

Second, check the underside of the plants’ leaves for clusters of bronze to red eggs. If you find some, pick them off and destroy them. Trellising vining species of squash and melons, as well as using protective covers over your plants, can reduce your chances of having a squash bug infestation.

Continue being vigilant throughout the growing season, killing eggs and the bugs themselves as you find them. Check around the crown of the plant, a favorite hiding place for eggs, nymphs, and adults.

Garden sanitation is an important step in preventing squash bug infestations. Once you have harvested your plants, pull them out and dispose of them. Leaving the spent plants lying on the ground creates hiding and overwintering sites for the adults. Compost or till under any other vegetation that is no longer growing. Continue to search for and destroy any bugs that have remained in the garden.

Following the above steps should keep the population of squash bugs low enough to prevent any serious damage. If your efforts aren’t enough and your garden has a squash bug infestation, consider chemical controls. Contact the WSU Master Gardeners’ Plant Diagnosis Clinic for recommendations. You can talk to an experienced clinician in person at the clinic at 400 Washington St. on Monday and Wednesday from 1 to 3 p.m. You can also contact them by phone at 667-6540 or by email at chelanmastergardeners@gmail.com.

A WSU Master Gardeners of Chelan County column appears weekly in The Wenatchee World. Casey Leigh is one of four columnists featured.