I have written several articles on the squash vine borer, and they can be a real problem, but they tend to stay confined to vines. A couple of years ago someone called the office and complained that bugs were eating her squash and cucumbers, leaves and all. I was puzzled, as I had never heard that the borer ate the entire plant. She brought some bugs in and after some research we determined they were squash bugs. The same night another gardener brought in the same bugs with the same story: They ate everything in sight.
The squash bug is common throughout the United States. It will attack all members of the cucurbit family, but are most common on pumpkins and squash. Their piercing and sucking mouthparts feed on the plant foliage, and late in the season they may also feed on the fruit. Evidence of the damage includes wilting leaves that will appear black or dried out.
The squash bug looks a lot like the stinkbug bug, but believe me, they are a lot more harmful. They are usually gray to black with the edges of the abdomen having orange and brown stripes. Nymphs are three-sixteenth to one-half inches in length. The young have a red head and legs with a green abdomen; however as the young age the red color will turn blackish grey.
The eggs are one-sixteenth inch long and have a yellowish brown to brick red color. Eggs are laid individually in groups of up to 12 on the underside of leaves. Each cluster of eggs is usually laid in a characteristic V shape pattern following the leaf veins. Eggs are laid from spring to midsummer and will take from one to two weeks to hatch. The eggs will become darker as they get close to hatching.
The adults overwinter and find shelter during the early fall under plant debris, around buildings, under rocks, etc. They emerge in the spring and fly to the fields and the cycle begins again. Both the adults and nymphs cause damage by sucking nutrients from leaves and disturbing the flow of water and nutrients, which cause the wilting. Before wilting, yellow specks will develop on the foliage that eventually turn brown. Under heavy feeding pressure, small plants can be killed and larger plants can have severe damage. Squash bugs will also feed directly on the fruit and they have become a serious problem in recent years. In fact, the gardeners that have contacted me claim the squash bugs multiply extremely fast and eat everything growing.
If only a few plants are affected, handpicking of the eggs and bug may be enough. Another option is to place shingles on the ground next to the plants. At night the squash bugs will go under the boards and can be destroyed in the morning. Using resistant varieties such as Butternut, Royal Acorn, or Sweet Cheese and maintaining a healthy plant through proper fertilization and watering are important.
If you have a severe problem, you may need to turn to an insecticide. I’m no different than most of the other Master Gardeners in that I don’t like insecticides or herbicides, but the squash bug is very difficult to control. The only products that I know that will control the squash bug have spinosad as one of the ingredients. Captain Jack’s Deadbug or Potato Bug have spinosad, and there may be others. Spinosad comes very close to being organic, and you may need to apply more than once. Again, read the label and use recommended amounts.