How to Control Squash Bugs – Identification and Strategies

Squash bugs infesting yellow summer squash in the garden.
My Garden Life
July 1, 2024
Table of Contents

By Kelly Miller

Squash bugs are among the most notorious common garden pests. It’s possible to control squash bugs before they destroy any plants, but it usually takes some planning and effort.

Let’s cover all you need to know to protect your zucchinis and pumpkins from squash bugs. We’ll step through basic squash bug facts, identification markers for different life stages, and strategies for squash bug control.

Life Cycle and Feeding Habits of Squash Bugs

The squash bug (Anasa tristis) is a sap-sucking insect native to North America. Squash bugs are common garden pests throughout most of the United States.

In winter, squash bugs are dormant. They take shelter under rocks, plant debris, or around building foundations. They emerge in spring and move to host plants, usually of the Cucurbita (squash) genus. The plants that squash bugs infest include:

  • Squash (zucchini, yellow squash, acorn squash, etc.)
  • Pumpkin
  • Cucumber
  • Watermelon, cantaloupe, and other melons
Many squash bugs crawling on the surface of a small pumpkin in a vegetable garden.

Squash bugs feed by sucking sap from plants. They mostly target leaves but also feed on vines and ripening fruits.

Late spring and early summer are spent feeding and mating. Egg laying occurs in June on the undersides of leaves. Eggs hatch after around 10 days, producing nymphs that immediately begin feeding on leaf sap.

How to Identify Squash Bugs and Squash Bug Damage

The first step to dealing with a pest is identification. Knowing for sure which pest you’re dealing with helps you determine the best ways to control squash bugs and prevents the unnecessary killing of beneficial insects. Here’s how to identify squash bug eggs, nymphs, and adults.

Squash bug eggs are:

  • Around 1/16 inch (0.15 cm) long
  • Yellowish or reddish brown in color
  • Usually in clusters of around twenty eggs
  • Found on the undersides of leaves, but sometimes on top of leaves or along stems
Control squash bugs by starting with removing eggs from underneath squash plant leaves.

Squash bug nymphs are:

  • Nymphs are smaller and less mobile than adults
  • Squash bug nymphs reach maturity after 4–6 weeks
  • Nymph bodies change from pale green in color to gray over time
Close up of squash bug nymphs emerging from eggs on a squash plant leaf.

Adult squash bugs are:

  • 0.5–0.75 inches (1.2–1.9 cm) in length
  • Dark gray or brown
  • Flat-bodied
Close up of an adult squash bug.

Squash bug damage usually occurs on young plants, especially when flowering, in early or midsummer. Sap-sucking creates splotches of small yellow spots on leaves. These areas later turn brown.

Note that several other pests and diseases similarly discolor squash plant leaves. If you’re not sure what’s damaging your plants, consult our guide to common squash diseases and pests

Methods to Control Squash Bugs

Squash bug control should occur in spring and early summer, when young plants are vulnerable. Squash bugs are less active in late summer and fall. Here are the best methods for preventing and controlling squash bugs in a home garden.

Prevention and Protection from Squash Bugs: Plant Selection, Timing, and Care

Butternut squash and acorn squash tend to be less susceptible to squash bugs. Meanwhile, Hubbard squash, yellow crookneck, and yellow straightneck squash are highly vulnerable.

Planting squash later in the season can prevent infestation and reduce the need to control squash bugs. Squash seeds can be direct sown as late as early July, depending on the region, for a fall harvest. Late-planted squash develop after most squash bug activity has settled down. 

For spring-planted squash, it’s helpful to keep plants covered until they blossom. Use a floating row cover or similar product that’s permeable to air, light, and water, but woven tight to prevent pest entry.

Rows of vegetables being protected from pests by use of a white mesh fabric row cover.

Mulching does not provide protection against squash bugs. In fact, mulch provides these pests with shelter. This doesn’t mean you shouldn’t mulch, but be aware that squash bugs may hide under the surface.

Keep your garden clear of old squash vines and other debris, especially at the end of the growing season.  This material provides food and winter shelter for squash bugs. Some gardeners intentionally leave decaying plant material on the ground for passive composting or to provide shelter for beneficial insects. In those cases, other more targeted prevention and eradication methods are required to control squash bugs.

Destroying Eggs and Bugs

Early detection is key for squash bug control. Eggs and nymphs are easier to kill than adults, which are more evasive.

During egg season (usually June), check the undersides of leaves. Crush the eggs or use a butter knife to scrape them into a cup of soapy water. Use these same methods to eliminate nymphs. This is a great way to avoid using insecticides in your vegetable garden to control squash bugs.

A soapy water pail works for adults too (they can’t swim, and the soap helps them die faster). Wearing gloves, simply flick the bugs into the soapy water, drown them, and dispose of them. Another option for manual control is to use a handheld vacuum to suck up the squash bugs around your plants.

Trap Plants and Overnight Traps

A “trap plant” is one that’s grown for the purpose of luring pests away from other crops. Trap plants provide a food that pests like even more than the protected “cash crop.” As pests congregate on trap plants, large numbers can be quickly eradicated. The proven trap crop for squash plants is blue hubbard squash. This winter squash variety is easy to grow in the same conditions as other types of squash and serves up an abundance of foliage that squash bugs can’t resist. Blue Hubbard squash also lures squash vine borer and striped cucumber beetles.

A blue hubbard squash ripening on a vine in the garden.

You can also create passive overnight traps for squash bugs by laying old wooden boards near your crop. The bugs are likely to congregate under the boards for overnight shelter. In the early morning or late evening, scrape them into soapy water or press hard on the board against the ground or another board to swiftly wipe out the cluster.

Learn More About Growing Squash

Squash plants are susceptible to pests and disease. However, if you can manage those threats, then squash is easy to grow and produces some of the most substantial garden veggies you could hope for. Learn more about growing the most popular type of squash in our guide on How to Grow Zucchini Plants.

Green and yellow squash in a wicker harvest basket in the garden.

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