Here are tips on how to identify, eliminate, and control squash bugs.
What are Squash Bugs?
Squash bugs are the bane of a gardeners' existance! They are very difficult to kill and cause havoc. These bugs inject a toxin into the plant and suck the sap right out of it.
The leaves will wilt, dry up, turn black, crisp, and brittle. Smaller plants will die.
How to Identify Squash Bugs
The squash bug is fairly large (over 1/2-inch long) with a brownish body and flat back. If you squash them, they will stink.
They overwinter in your dead leaves, vines, under boards, and even in buildings. They fly to the plants as soon as vines start forming to mate and they lay egg masses on the undersides of the leaves. You'll find adults beneath damaged leavles and near the plant crown.
Photo Credit: University of Delaware Cooperative Extension
How to Control Bugs
- Early detection is critical! You want to catch squash bugs before they grow into adults or they are very difficult to kill.
- Pick egg masses off the plants in the morning and later in the day. One reader fills a vase with water and liquid detergent and flicks the squash bugs into the water. Once the bugs are dead, it's fine to dump the water anywhere.
- Place a board or shingle in the garden at night. During the night, both adults and nymphs will congregate underneath the board. Squash between two hard surfaces in the morning and dispose.
- Insecticides (such as carbaryl/Sevin) are most effective if applied when eggs are hatching. See your garden center for controls that are locally approved.
- Keep checking your plants, at least daily. If there are no more than a few vines infected, keep collecting and destroying the bugs and crushing the egg clusters that you find on the undersides of leaves.
- Consider keeping vines covered until blossoming begins. Remove the cover for pollination needs. There is only one generation of squash bugs per year.
- Avoid deep, cool mulches like straw or hay that provide an environment that these bugs seem to love.
- Prevention is key: In the fall, be sure to burn or compost old squash vines to rid your garden of any possible shelters for breeding and over-wintering.
- Rotate your crops.
- Select varieties of squash that are resistant to the squash bug if you have a big problem.
See our Squash & Zucchini page for more plant care tips.