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Extension Corner - controlling squash bug populations in Castle Valley

Carbon County Extension agent

Now that summer is in Castle Country, gardens are growing.

While harvesting crook-neck and zucchini squash, I have seen more squash bugs in my garden than in past years.

I have even found adults and eggs on my cucumbers.

About five-eighths of an inch long, squash bugs are large insects that belong to the class of true bugs. They are grayish brown in color.

Right now, the squash bugs are mating and laying eggs on the underside of leaves and stems. They have piercing mouthparts and feed by sucking the juices from the plant leaves and stems.

At the same time, the bugs inject a little toxin into the plant. The toxin gums up the vascular tissue and causes apparently healthy plant to suddenly wilt and die. I have seen the squash bugs kill a zucchini plant, which I thought was impossible.

A couple bugs are generally not a problem for squash plants. But when the eggs hatch, a large number of nymphs can be seen feeding on the leaves and stems. The nymphs are a grayish color and have soft bodies that are similar to the adults, only smaller and less developed.

It is best to do as much control as possible before the eggs hatch. Early in the season, the best control method is to catch and kill any adults that people can see.

The adult squash bugs can usually be found low on the plant on the underside of leaves and stems. The adult insects like to hide at night a small board placed near the plant can act as a trap for many of the squash bugs.

People should check under the board in the mornings. It is also important to remove any eggs that have been laid.

Eggs can be found on the underside of leaves and stems, usually - but not always in the V shape by the veins. The eggs can be scraped off with a fingernail or pocket knife and squished. A little damage to the leaf will be less of a problem than having several dozen squash bug nymphs sucking the life out of the plant.

Once eggs start hatching, chemical control is usually warranted. Products containing carbaryl are typically labeled for squash bugs. The powder form works well, but is difficult to apply to the underside of the leaves.

People should follow the label directions and observe pre-harvest intervals before eating the produce.

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