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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>Greg Johnson</span> Thu, 08/07/2014 - 09:29
I'm Having Some Major Problems With Them In My Tomato Plants. They Started In The Squash, Bypassed The Cucumbers And Headed Directly Into The Tomatoes Where They Can Defoliate Most Of A Plant In A Day. It's Crazy I Don't Even Believe Tomatoes Are Good For Them I've Watched Them Bite Into The Fruit And Fall Off Dead. Would Getting Them Out Be The Same As Squash And Cuc's? Need Help, Thank You, Greg Johnson
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 08/08/2014 - 10:02

It's unusual for squash bugs to attack tomatoes, preferring cucurbits such as squash and cucumbers. A similar-looking bug called the stink bug (aka shield bug), does attack tomatoes, but they tend to focus on sucking the juices from the fruit. The leaf-footed bug does similar damage. You might want to bring a bug to your local Cooperative Extension or a garden nursery horticulturist to ID it.

For control of squash bugs on tomatoes (and other true bugs such as stink bugs), it would be about the same as mentioned above for squash: handpick; use rowcovers; remove any eggs that you see under the leaves; place boards around your tomatoes and look under them in the morning, and destroy any pests there; sprinkle diatomaceous earth around the base of your tomatoes, to work as a barrier; remove weeds around the area; and remove mulch at season's end, to get rid of hiding places for overwintering adults. For more information about squash bugs, see:

http://www.vegedge.umn.edu/VEGPEST/CUCS/squabug.htm
 

Defoliation of tomatoes is often caused by caterpillars--check if you can find any hiding among the leaves, such as the large tomato hornworm. Beetles (such as the Colorado potato beetle) and whiteflies can also harm leaves. Diseases can also cause leaves to drop.

For a list of common tomato pests, including the stink bug, see:

http://extension.umd.edu/learn/insect-pests-tomato

 <span>Roger Racurl</span> Mon, 08/04/2014 - 22:12
I found many, many of these bugs this year on our zuchinni plants and the cucumbers. Once I noticed them, I went on a daily morning hunt for adult bugs, the nymphs, and the eggs. At first, I was killing 20 or more adults and innumerable nymphs and about a billion eggs! I used the dishwashing soap and spray bottle method and they just die right away. It does effect the leaves a bit, but it sort of gave an interesting look to the leave itself and I don't think that it hurt it in any major way. Soap and a considerable amount of diligence and our zuch's and cukes are BACK!
<span>Shermie Schafer</span> Sun, 08/03/2014 - 12:46
Have a few of these I've found INDOORS EVEN BEFORE plants emerge. Have NO other veggies; only flowers. Exterior base of house has been treated for mosquitoes and spiders; will this help? Add SEVIN? Anything I should apply INDOORS, and where? Thanks!
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 08/04/2014 - 11:42

Sometimes, the odorous squash bug will overwinter indoors and are a real nuisance. Avoid squishing them as they will smell and stain.  The best you can do is to try to identify where they are entering. Seal all windows and building cracks; caulk all incoming pipes and wires. And, as you said, spray the exterior of your home with a pesticide (not inside). Do this in the fall. You'll need to ask your local cooperative extension for an insecticide that's approved in your area.

 <span>Suzette F Byrd</span> Mon, 07/28/2014 - 13:10
I find 1 or 2 adult squash bugs almost every other day, crush them with rocks, & then I am finding 1 or 2 leaves with 5 -25 eggs on each leaf once or twice weekly & snipping off those leaves,sealing in zip lock bags & into the rubbish they go. Where r they coming from?!? Will it ever end?!? ! :-\
<span>Kanga311</span> Mon, 07/28/2014 - 22:08
Oh my goodness...I'm battling these things daily. I find 8-10 on my cucumber plant each morning. And every time I catch them, they're always end-to-end in the middle of a mating session! When will this end is my question too!!! D:
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 07/29/2014 - 12:05

A six week  life cycle is the average so you may have two generations of squash bugs before harvest in the fall. Squash bugs start laying eggs when your plants are young in early summer. Eggs hatch after about two weeks and the nymphs feed for about a month before becoming adults. The adult females continue to lay eggs during this time

 <span>Kelly Ogle</span> Sun, 07/13/2014 - 15:18
I have found the only way to save my squash, pumpkin, and cucumber vines (yes, once they kill all your squash they'll go for your cucumbers!) 1) use a decoy squash plant or two out in the open 2) grow your real squash in raised beds/boxes under ag ribbon 3) once they show up, pick over your plants every day 4) squish the eggs too! if you just scrape them off the leaves and they drop to the ground they'll still hatch 5) use the board/cardboard trick mentioned above 6) sprinkle diatomaceous earth around/on your squad plants- it cuts into their exoskeletons and kills them (warning: it also kills beneficial insects) I don't use soap on my plants except in very dilute amounts- it does cause burning to the leaves in hot weather.
<span>David Hyatt</span> Wed, 06/18/2014 - 15:17
I live in the high desert in southern california. I'm pretty sure I'm the only house with a garden in quite a large radius and this is my first garden. I didn't think I'd have to deal with a lot of specialized garden bugs because of my isolation from farms, but these showed up and I can't bring myself to grab them lol.. I would up zip tying a couple pieces of sponge to bbq tongs so I could grab them without crushing them and then dump them in a red solo cup of water and laundry detergent, they drown in a minute or so. Never gardened before, did a lot wrong but learning a lot and going to scale up big time next year :) Thanks for all the free resources!!