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How to Identify and Get Rid of Squash Bugs in the Garden

Image Credit:
Niney Azman/Shutterstock
Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Let’s squash the squash bug population! Squash bugs can be the bane of a gardener’s existence, sucking the life out of your precious cucurbit plants. Here are tips on how to identify, control, and get rid of squash bugs in your garden.

What Are Squash Bugs?

Squash bugs are very difficult to manage once their numbers get out of control and can cause a lot of havoc.

They are most commonly found on squash plants (hence the name), such as pumpkins, winter squash, and zucchini, but they may also affect other crops in the cucurbit family (like cantaloupe, cucumbers, and watermelon). Other pests that are commonly found on squash include squash vine borers and aphids.

Generally, they attack young tender plants and seedlings, causing them to wilt and die. However, they cause little damage to plants in late summer and fall.

Note: 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.

Identification

How to Identify Squash Bugs

The adult squash bug is a flat-backed insect that is fairly large (over 1/2 inch long) and usually dark gray to dark brown.

The edges and undersides of the abdomen have orange stripes. Although they can fly, they often simply walk around on plants.

Young squash bugs, or nymphs, may be gray or light brown and have black legs. They move quickly and often congregate in groups on the undersides of leaves.

Squash bugs overwinter in dead leaves, vines, under boards, and even in buildings.

In early June, they mate, laying small clusters of eggs (about 20) on the undersides of the leaves, and the females will continue to lay eggs through mid-summer. You’ll find adults beneath damaged leaves and near the plant crown, where they use their piercing mouthparts to suck out nutrients from the plant.

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 become very difficult to get rid of completely.
  • Pick bugs off the plant early. Fill a bucket with water and liquid dish soap and flick bugs into soapy water. Once the bugs are dead, it’s fine to dump the water anywhere.
  • Pick egg masses off the plants in the morning and later in the day. 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 10 days, so be sure to check for them on at least a weekly basis.
  • Place a board or shingle in the garden at night (or pieces of newspaper). During the night, both adults and nymphs will congregate underneath the board. Squash between two hard surfaces in the morning and dispose of them.
  • 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.
  • Remove plant debris during the growing season to reduce sites where squash bugs can hide. 

Using pesticides

Insecticides are not effective in managing squash bugs once they are adults, so don’t bother trying.

In the event that you catch the squash wilting very early in the season and you catch this when eggs are hatching, then insecticide application is probably needed to manage it. See your local garden center or cooperative extension service for controls that are locally approved. The best time to apply pesticides is early morning or late at night (during minimum bee activity). Be sure to spray underneath the leaves, where most squash bugs are found.

It is not necessary to treat squash bugs found in the garden during late summer or fall.

Squash bugs on pumpkin

How to Prevent Squash Bugs

  • Prevention is key: In the fall, burn or compost old squash vines to rid your garden of any possible shelters for breeding and overwintering.
  • Avoid thick layers of mulches like straw or hay that provide an environment that these bugs seem to love.
  • Practice crop rotation.
  • Consider keeping squash plants covered until blossoming begins. Remove the cover for pollination needs. There is typically 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.
  • Clean up cucurbits and other plant matter in the fall to reduce the number of overwintering sites.

Garden Pests

About The Author

Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the digital home of The Old Farmer’s Almanac. She leads digital editorial strategy and publishing across a wide range of Almanac sub...

Read more from Catherine Boeckmann

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Comments

<span>Candace Arnette</span> Sun, 04/29/2018 - 20:22
Was wondering if anyone has had any luck using diatomaceous earth on plants, eggs, adults and whatever? Thanks
<span>Rosemarie</span> Mon, 07/23/2018 - 13:34
I have used DE for these bugs. It does not work on adults or eggs just the nymphs that have thin skins. The de will scratch the shell of the bug and dehydrate them, You must reapply after it rains,
<span>Nichole</span> Mon, 05/21/2018 - 17:56
I have tried the Diatomaceous Earth & for the most part it did work. However I just checked on my plants today & the little buggers seemed to lay eggs on the belly of a few leaves. I will try again. I also did not know if I cut the leaves that had the eggs on them & then dusted if that would be effective too???
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 05/01/2018 - 10:19

Diatomaceous earth (DE) will kill squash bug adults and nymphs, but because it will need to be applied to the leaves and stems of plants to be effective, there's also a chance that it will kill pollinators, like bees and butterflies, as well as other beneficial insects, like ladybugs. If you do apply it to plants, apply it in the early morning or late evening and avoid applying it on or near flowers.

 <span>Carolyn</span> Fri, 07/05/2019 - 11:10
I am reluctant to use DE in the garden, because it will harm pollinators and earthworms. No one has mentioned praying mantis or Asian wasps as a control method. Would this be a realistic solution?
<span>Nichole</span> Mon, 05/21/2018 - 17:57
If I cut the leaves that have a few eggs on them will that harm the overall plant??
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 05/22/2018 - 16:04

Removing an entire leaf would be overkill; it's better to just squish the eggs. Cutting the leaves could expose the plant to viruses and mold.

 <span>Danna</span> Wed, 09/27/2017 - 18:07
I've found bugs and eggs on my gourd plants. I'm not sure if they're squash bugs even though the description seems to match the pictures vary slightly. The adults I'm finding are black in the front and back with orange on the outter mid section of the bug. The eggs are mostly under the leaves but not always. There seems to be tons of dark green eggs as well as some lighter cream colored which are almost white. Please help me identify these critters so I can try to get rid of them! I wish I could share a picture here of what I've found! Thank you.
<span>Charlie Mcclelland</span> Mon, 09/18/2017 - 13:15
I do something I have never seen mentioned as a way to kill squash bugs. I spray the plants and ground thoroughly. Then I wait a couple of minutes. The squash bugs begin climbing to the top of the leaves--I assume to get dry. Wearing gloves I simply squash the bugs and lay them out for a "body count." By the time I get to one end of the plants, more bugs have climbed to the top of the other end. I repeat going down the row until there are no more bugs. If I have time, I soak the ground and plants again just to make sure. It worked until I missed a day, then the plants suffered.
<span>Tanna White</span> Thu, 07/12/2018 - 22:50
For the most part, we control squash bugs by putting the hose down in the hole of the plastic and forcing them to the top of the plastic with the water. We hand pick them off the plants and kill them and their eggs. Now, after reading what everyone else is doing though, we are going to plant ALL of our winter squash in a different place and rotate each year. We are NOT going to use black plastic Also, I think putting a couple of boards down around by the plants makes sense to get squash bugs to get under them at night and kill them the next morning. Insecticide doesn't work very well, but it will seep into the plants/fruits and then our bodies and we know that it is wreaking havoc on humans!!! :(