Squash Bugs


Squash bugs (Anasa nistis) are present in large numbers attacking squash vines throughout the state.  Overwintering as adults, these bugs emerge in spring to mate and begin laying eggs.  The eggs are usually laid in groups of 10 or more on the underside of leaves in the angles formed by veins.  Spider-like nymphs hatch from the eggs and go through several instars before maturing to adults.  Nymphs look more like adults with each molt.  There is only one generation per year but the egg-laying process takes place over a long period of time, so one can easily find adults, eggs, and several instars in the garden at the same time.

Nymphs and adults feed on squash leaves and stems.  While feeding, they inject a toxic substance into the vine causing a wilt that resembles bacterial wilt of cucumber.  Leaves and stems then turn brown and brittle.  Squash bugs also feed on ripening fruit.  They attempt to hide when disturbed and can be found under plant debris.

Control squash bugs early by destroying eggs and overwintering adults.  Row covers can be used to protect early growth, but must be removed for pollinators.  There are insecticides labeled for control of squash, but be cautious when applying to avoid killing pollinators.  Garden and field cleanup to eliminate overwintering sites for adults will reduce the population next season.