What is it?
Squash bugs or Anasa tristis are harmful to cucurbits in both their young nymph stage and as adults. Although they attack many members of the cucurbit family including cucumbers, gourds, muskmelons, summer squash, pumpkins, watermelon, and winter squash, their damage is most extensive in pumpkin and squash plants.
What does it look like?
Squash bugs are flat-backed bugs which usually grow no larger than 1/2 in length. Typically they can be found in clusters on cucurbit family plants and they come in a variety of colors. Squash bugs can be anywhere in the range of colors from bright green to dark brown or grey.
Damage from squash bugs occurs on cucurbit family plants in the form of wilting leaves. As the leaves wilt, they take on black color and become crispy and dry. This is caused by Anasa tristis sucking the sap from the leaves of the plant as well as the stems of the cucurbits.
How does it manifest?
Adult squash bugs are usually a dark brown color. Often times they are mistakenly called stink bugs, but this is not a correct term. However, the squash bugs do emit an offputting odor if they are stepped on or otherwise crushed. The adult female squash bugs lay eggs that are a bright brick-red color on leaves each spring.
They lay these eggs in clumps or clusters. Each growing season one generation will hatch from the eggs and begin injuring and killing cucurbit family plants by sucking the sap from them. Even though only one generation is produced they can cause considerable damage if your plants are infested.
What can you do about it?
When you find squash bugs in your garden, you will also find that they are hard to control and incredibly elusive, hiding frequently from sight. Once you note the bugs, even if it seems there are only one or two, or if you find the characteristic brick-red eggs on the leaves you will need to treat the infected plants with pyrethrins or carbaryl containing insecticide.
You will need to repeat applications at one-week intervals until no further damage or signs of bugs occur. A way to avoid or at least reduce the incidence of squash bugs in your garden is to plant varieties of the cucurbit family which are resistant to these insect pests.