Squash Bugs

Posted: May 9, 2015

Squash bugs, Anasa tristis, are the bane of squash and pumpkin growers. These insect pests may also suck the sap from leaves, stems, fruit and vines of gourds, melons, and cucumbers.
Photo Credit: Jeff Hahn, University of Minnesota

Photo Credit: Jeff Hahn, University of Minnesota

Squash bug adults are 5/8” long, oval shaped, gray to dark brown with light orange and brown stripes on the abdomen. Females lay a cluster of light orange to brick red eggs on the underside of a cucurbit leaf.  The eggs start to darken in color as they approach hatching. Nymphs emerge in 7 to 10 days after the eggs are laid. The nymphs vary in color from green abdomens and red or black heads to changing shades of gray as they mature. All stages will cause feeding damage – leaves rapidly wilt, blacken and die. On fruit, feeding damage results in corky spots forming on the surface of the fruit and/or dead, sunken areas that allow entry of other pathogens.

Adult squash bugs overwinter in protected areas, such as buildings and plant debris or even under rocks. In mid-June, the adults start to emerge. But they do not look for your cucurbit plants until the plants are larger and starting to “vine out.” The adults are hard to locate on the plants because they quickly hide when disturbed. Early detection of eggs and nymphs is important because adults are harder to manage.

Eggs can be easily crushed while attached to the leaf. Nymphs and, even adults, can be knocked off into a pail of soapy water, if there are only a few plants affected. Remember, they move quickly when disturbed so try to be faster!

Adults like to spend the nights at the base of the plants, so consider placing boards or newspaper at the base. Early the next morning, go out to collect and destroy the adults before they climb back up onto the stalks and leaves.

Planting resistant varieties may also give you some relief. Butternut and Royal Acorn squash are fairly resistant. Most pumpkins, ‘Black Beauty’ zucchini, yellow crookneck and straightneck squashes are highly susceptible to squash bugs.

After the final harvest, a very good cleanup of old plant debris will help to make it harder to find an overwintering sight.

For more information visit the Penn State Entomology website.


Contact Information

Sharon Telesky
  • Luzerne County Master Gardener