Adults are about 5/8 inch long, blackish brown above and mottled yellowish-orange beneath. They have a flat back the outer rim of which is orange, in high contrast to the dull brown wings. Squash bugs emit an unpleasant odor when crushed. The five instars take a total of about 33 days to develop. The first instar is light green and about 2.5 mm long when it hatches. Succeeding instars progress to about 10 mm in length and are colored increasingly darker shades of gray. Young nymphs are very gregarious. Eggs are elliptical and bronze colored. They are most often found on the underside of leaves in groups of equally spaced eggs.
Damage:Squash bugs can cause severe damage to squash and pumpkin but also attacks cantaloupe, cucumber, watermelon and other cucurbits. Both adults and nymphs feed on plant sap. They secrete toxic saliva into the host plant. Leaves wilt, turn black and die. Sometimes an entire plant or section of a plant dies while nearby plants remain healthy. Greatest damage comes in mid to late summer when nymphs are numerous.
Cultural Practices. In home gardens and other small plantings adults and egg clusters can be collected by hand and destroyed. Squash bugs can be trapped by placing boards, burlap, or other suitable hiding places on the ground in and around the garden. Early every morning when the boards are turned over, the bugs that have hidden underneath can be "squashed". Examine plants frequently and remove or crush any eggs or bugs.
Squash bugs are difficult to control. It is important to avoid leaving hiding places such as crop residue, which can be used for overwintering sites after the crop is harvested.
Insecticides. Adults are very difficult to control with insecticides and it is advisable to target the nymphs if it is decided to try chemical control. Be sure to read the entire label and carefully follow all instructions when using any pesticide.
For More Information See: The University of California Pest Management Guidelines
Squash Bugs in the Low Desert