Squash bugs are another southern insect that is now common north of I-70. They feed on squash (winter types preferred over summer), pumpkin and also can be found occasionally on gourds and melons. Squash bug, Anasa tristis, causes vines to wilt and leaves to turn black and crisp. Symptoms may be mistaken for lack of water during dry periods. After fall frosts kill vines, insects will congregate on the sunny faces of unripe fruit and cause injury by further sap sucking.
The adult is gray-brown and about 5/8 inch long. Eggs are brick-red and are laid in clusters in the angles between veins on leaf undersides. Young bugs are green and red. Older bugs develop a grayish-white color.
Manage insects by thorough fall garden cleanup to deprive over-wintering adults of shelter. Mulches tend to increase problems as they give insects cover. Stimulate fast growth of vines by planting in warm weather and fertilizating. Hand pick adults and crush eggs or remove leaves bearing eggs. Diatomaceous earth and pyrethrin applied to the base of the plant may be effective. A few other insecticides, including those with esfenvalerate, permethrin, or carbaryl as the active ingredient, can also control squash bug.
For more information, see the following Colorado State University Extension fact sheet(s).
For more information, see the following Planttalk Colorado™ script(s).
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Updated Tuesday, October 13, 2015