Age-Old Wisdom meets Modern Tools
How to Identify and Get Rid of Squash Bugs
The squash bug is sometimes confused with a stink bug, but it can cause much more damage to your plants.Barbara Pleasant
What are those bugs on your squash? Squash bugs, probably. Here are tips on how to identify, control, and get rid of squash bugs in your garden.
What are Squash Bugs?
Squash bugs can be the bane of a gardener’s existence! They are very difficult to manage and can cause a lot of havoc. Squash bugs are most commonly found on squash plants (hence the name) such as zucchini, winter squash, and pumpkins, but they may also affect other crops in the cucurbit family (like cucumbers, cantaloupe, and watermelon). Other pests that are commonly found on squash include squash vine borers.
Squash bugs are often mistaken for stink bugs, as they are similar in appearance and both have a foul odor when squashed. However, stink bugs are wider and rounder than squash bugs.
How to Identify Squash Bugs
The squash bug is fairly large (over ½-inch long) with a brownish or gray body and flat back. The edges and undersides of the abdomen have orange stripes. They are able to fly, but they often simply walk around on plants. Young squash bugs, or squash bug nymphs, are gray and have black legs. They move quickly and often in groups on the undersides of leaves.
Photo Credit: University of Massachusetts Amherst. Newly-hatched squash bug nymphs are small with black legs and move around in groups.
Squash bugs overwinter in your dead leaves, vines, under boards, and even in buildings. They fly to garden plants to mate as soon as vines start forming, and they lay egg masses on the undersides of the leaves. You’ll find adults beneath damaged leaves and near the plant crown.
Photo Credit: University of Delaware Cooperative Extension. Squash bugs lay small brown eggs on the undersides of leaves.
Squash Bug Damage
These bugs inject a toxin into the plant and suck the sap right out of it with their sharp, sucking mouthparts. This causes yellow spots that eventually turn brown. The leaves will wilt because the damage prevents the flow of nutrients to the leaves, and then they will dry up and turn black, crisp, and brittle. The leaves also sometimes have ragged holes. Smaller plants will die, and squash bug feeding can decimate young fruit.
The wilting can resemble bacterial wilt, which is a disease spread by cucumber beetles (yet another squash pest), so be sure to find the bugs or eggs and identify them correctly.
Control and Prevention
How to Get Rid of Squash Bugs
- Early detection is critical! You want to catch squash bugs before they grow into adults or they are very difficult to get rid of completely.
- Pick egg masses off the plants in the morning and later in the day. One reader fills a vase with water and liquid dish soap and flicks the squash bugs into the water. Once the bugs are dead, it’s fine to dump the water anywhere. You can also simply scrape the eggs off the leaves with a butter knife and let them fall onto the ground, where beetles will eat them. Eggs hatch in about ten days, so be sure to check for them on at least a weekly basis.
- 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 local garden center or cooperative extension service 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.
How to Prevent Squash Bugs
- 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.
- Avoid deep, cool mulches like straw or hay that provide an environment that these bugs seem to love.
- Practice crop rotation.
- Consider keeping vines covered until blossoming begins. Remove the cover for pollination needs. There is only one generation of squash bugs per year, and you can avoid them by covering your plants for the first month of spring. You can also delay planting your squash until the early months of summer.
- Companion planting can be useful in repelling squash bugs. Try planting nasturtium and tansy around your plants that are commonly affected by squash bugs.
- Select varieties of squash that are resistant to the squash bug if you have a big problem. ‘Butternut’, ‘Royal Acorn’, and ‘Sweet Cheese’ varieties are all more resistant to squash bugs.