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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>Tom Denton</span> Tue, 07/24/2018 - 18:00
I've found an effective solution for killing the squash bugs. Doctor Bronner's eucalyptus soap. You have to be careful about the dilution. You don't want it too stringent or you will damage the plant. When you see bugs, spray the solution on them. They will be dead in 30 seconds, trust me. Just die on the spot, especially the smaller ones. (If you can see the big ones, squash them by hand.) In order to be careful about the plants, I water the leaves I've sprayed after the bugs are dead in order to get the solution off the leaves. If you've got a big infestation, you'll have to do this regularly. But it kills them dead, as the Raid can says.
<span>Stacy Morris</span> Sat, 09/08/2018 - 18:36
For Tom Denton, Does it have to be eucalyptus because I I think I have this brand in peppermint.
<span>John</span> Tue, 08/28/2018 - 23:18
What is the dilution of that Dr Bronners soap that you use to battle the squash bugs?
<span>Gail Petchenik</span> Sat, 08/25/2018 - 17:04
This sounds great! I ordered some soap from amazon. What is the dilution ratio u use?
<span>Barbara Degrande</span> Sun, 08/19/2018 - 10:22
What was your dilution?
<span>Gina</span> Sun, 08/05/2018 - 15:49
I just pulled out my zucchini plants because they’re basically dead and infested. I got one zucchini. One. And it has weird rough bumpy skin. I’m not even sure I want to eat it. I tried horticulture oil, scraped bugs into a cup of dawn and water, scraped off eggs with a butter knife, stomped on adults. I didn’t try and insecticide because I’m trying hard to be organic. But right now I’m so upset and disgusted by these bugs that if I had Napalm I’d use it. I did have weed fabric down to act as a barrier from weeds and keep moisture in but after learning that the squash bugs hide under it and possibly will over winter under it; I pulled it out. I barely have any tomatoes also; the plants are brown on the bottom but seem like the tops are ok. I’m not sure what else to do to kill the squash bugs that are left behind in the dirt. I’m hoping they’ll die now that there’s no more squash plant to feed them. I’m going to clean out the garden and look into some sort of way to eradicate what’s left in the soil eggs nymphs and what ever else can be lurking in there. I’d light the whole thing up if it wasn’t so close to the house!
<span>S Gandy</span> Thu, 08/09/2018 - 00:13
Your brown spots on tomatoes are blossom end rot. Plants need calcium. You can get a Blossom end rot spray to correct. When I plant tomatoes in the spring I stick 3 Tums in the hole and I never have blossom end rot anymore. I read to put down black plastic to cover your garden bed. Leave it for 2 weeks and the heat under there is supposed to kill bugs and weeds. I am going to try this. Need to research some more.
<span>Dena Baldwin</span> Tue, 06/26/2018 - 13:07
I'm with you on tried everything! I even planted my zuccini in a wagon & moving it 1 or 2 times a day, FAR!!! Nope, they followed. So I pay $1.49 per pound, for the same squash l grew out west at a rate I supplied the whole extended family.
<span>Handtalker 55</span> Sat, 06/30/2018 - 13:45
Can plant squash in fall. No bugs
<span>Ben</span> Sun, 08/13/2017 - 18:25
What are you suggesting to cover the plants with until the blossoming begins? You say plant the squash till later at the beginning of summer meaning late May or early June! Will that give sufficient time for the squash to mature? I find that once the squash has finished they move to the cucumbers.