I have found another insect preying on my garden. It is the squash bug which is common throughout the United States. It mainly attacks squash and pumpkins but can also attack other plants in the cucurbit family, such as cucumbers. Squash bugs suck the sap out of leaves and cause yellow spots that later turn brown. It is most important to control squash bugs when the plants are young seedlings and when they are flowering. They can cause young plants to wilt and die. Squash bugs are not a problem if you see them feeding on plants in the fall.

Adult squash bugs are flattened, large insects. They measure 5/8 inch long and 1/3 inch wide, usually dark gray to dark brown in color. Their abdomens have alternating orangish and brown stripes. The eggs are oval shaped, 1/16 in long, and yellowish to bronze. The nymphs hatching from the eggs range in size from 1/10 to ½ inch in length as they progress through five stages called instars.

At first, the young nymphs have a light green abdomen and black heads and legs. As the nymphs grow larger, they first turn light gray and then brownish gray, with black legs and antennae. Squash bugs can live through the winter as adults in sheltered places, such as under plant debris, around buildings or under rocks. When adults come out in the spring, they fly to growing cucurbit plants to feed and mate. Female squash bugs lay small clusters of eggs (about 20) on the undersides of the leaves, especially between the veins where they form a V. Eggs may also be seen on stems. The females usually start appearing in gardens in early June and continue to lay eggs through mid-summer. Eggs hatch in about 10 days and nymphs mature in about four to six weeks. Both adults and nymphs run for cover when disturbed.

One generation develops each year, although it is possible that in some summers there is a partial second generation. The life stages overlap and all of them can be seen at any given time during the growing season. In the fall, especially after the vines have died, the adults and nymphs group together on squash fruits. The nymphs die when the temperatures drop to freezing. The adults fly or crawl to sheltered places for the winter.

Early detection of nymphs is important, as adult squash bugs are difficult to kill. Remove and kill nymphs and adults by dropping them into a pail of soapy water. This is effective only if a few plants are affected.

Removal of squash bugs can be challenging because they hide under leaves and move quickly when disturbed. Trap squash bugs by laying out boards or pieces of newspaper. Squash bugs will group under the boards at night; you can then collect and destroy them in the morning. Remove plant debris during the growing season to reduce sites where squash bugs can hide. Clean up cucurbits and other plant matter in the fall to reduce the number of overwintering sites.

Pesticides should only be applied, if plants are wilting early in the season (due to squash bug feeding). The best time to apply pesticides is early morning or late at night (during minimum bee activity). Be sure to spray underneath the leaves, where most squash bugs are found. It is not necessary to treat squash bugs found in the garden during late summer or fall. For an organic method of eradicating the insects,, you you should remove them by hand and place them in a container of soapy water. Happy gardening!

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