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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>Pamela</span> Mon, 09/18/2017 - 11:44
This is exactly what has been invading my garden the latter part of the summer/early fall. Not only have I seen them in my zucchini plants, but also they invaded my greenhouse and they literally sucked the life out of many of my tomatoes. They appeared to be laying eggs in them. (Yuk!) We have had a garden for a few years now and never had this happen before. We are in Southern Oregon and now that the overnight temperatures have dipped to the low 40s, the bugs are finally gone. I have so many zucchini/squash plants, they were unable to take them over, thankfully.
<span>Pam</span> Mon, 09/18/2017 - 09:16
I have never had this happen before. I am getting what appear to be squash bugs attaching themselves to my first and second floor screens. I have researched every bug and these definitely look like squash bugs with the body shape and color, and not stink bugs. I have been flicking them off the screens and when on a window ledge spray them with hair spray. Has anyone else experienced this, or can tell me why this is occurring. I am from the far northwest side of Chicago.
<span>Tiffany Tocco</span> Wed, 03/20/2019 - 09:57
I think what you are seeing trying to invade you house is actually Brown Marmorated Stink Bug. The reason you have not had them in the past is because they are not native to USA and invasive. See the government article below. Prevention is the best plan as once they are there for the season... they will be there all season. I have had some luck with dryer/bounce sheets between the window and screens. Best of luck with Stink bugs. invasivespeciesinfo.gov- then search brown marmorated stink bug
<span>Diane Jakubowski</span> Wed, 03/07/2018 - 23:44
I have found the same problem! On my screens and windows. Now finding inside windows on 2nd floor. Been living here for 10 years never seen these bugs before
<span>Diane</span> Wed, 03/07/2018 - 23:46
Forgot to mention I'm from Green Bay WI...
<a title="View user profile." href="/author/editors">The Editors</a> Thu, 03/08/2018 - 12:54

Are you positive it's a squash bug? Some house pests such as the Western Conifer Seed Bug resemble squash bugs.

Either way, it's important to look around your home for any tiny gaps around pipes, pipes and electrical lines, vents, overhangs, and foundation. Where are they coming from? Then seal or caulk all those gaps.

In the fall, spray the exterior of your home with an approved insecticide. Speak to your state's local cooperative extension to see what's approved. You might need to consult with a professional pest control.

If they're in your home, vacuum up the bugs or spray them with a dish soap/water solution and sweep them up.

 <span>Gayle</span> Mon, 09/18/2017 - 18:30
We have the same problem here in south central New York. They are trying to find a way into the house to hibernate for the winter. They are very annoying.
<span>Shirley</span> Fri, 04/26/2019 - 15:01
Stink bugs, a relative of Squash bugs, are invading the Chicago area. I had hundreds infest a bedroom last year through a loose screen. I vacuumed them (it may make your vacuum smell til you change the bag). I had them in the bedding, behind pictures, in drawers, in photo albums!!! They don't destroy anything but are a definite nuisance. They do not breed over the winter in your house. Some say using soapy water in spray bottle around your windows works.
<span>Vance</span> Fri, 09/08/2017 - 16:26
I have tried EVERY remedy imaginable for killing or repelling (adult) squash bugs, and NONE of them has ever worked. I am convinced that all of the home remedies out there are a waste of time. Immature squash bugs are easy to kill, but the adult bugs (which are the ones that show up first), are a different story. Checking each vine daily, and physically removing (and smashing) the bugs and eggs by hand (or duct tape) DOES help, but you never find them all, and this becomes very time-consuming as the plants get larger. And if you ever have to skip checking for a day or two, you are likely to find your plants dead when you return. Picking the bugs off by hand has never been a good solution for me. Having said that, I HAVE found a way to get plenty of squash. The ONLY thing that has worked for me is to plant 2 or 3 times more squash plants than I really want. Yes, the squash bugs WILL still eventually kill them all, but not all at once. So, if you plant extra plants, AND check for bugs as often as you can, you can probably get all of the squash that you want. For me, that means planting 15 plants or so, instead of the 5 or 6 plants that I REALLY want. To save space (since I don’t really WANT to plan 15 squash plants!), I plant them between my sweet corn rows, and the squash plants seem to like that just fine. I think they actually do a little better there, than in the full Kansas sun. For those that are interested, here are the many failed squash bug remedies that I have tried over the years. • I have tried spraying the plants regularly with Sevin (and every other pesticide). Sevin and other over-the-counter pesticides are totally ineffective against the adult squash bug. But I still tried. I used liquid spray on top AND undersides of leaves, and generously on the main stalk. I used Sevin dust to cover the ground around the plants. And I have sprayed the bugs directly. Nothing would kill the adult bugs. • I have tried spraying the bugs with a mixture of dish soap and water. This did not bother the bugs at all. • I have tried placing boards around the base of the plants, as I have read that the bugs will hide there, making them easier to find and kill. I have seen many online sources suggest this, but I have found it to be totally ineffective. A healthy squash plant will get fairly large, and their long vines and large leaves make it very easy for the bugs to hide. I have seen the bugs circle around a stalk to hide as I look around the plant. With mulch around the plants, the bugs can pretty much hide anywhere, and usually NOT under the boards. I even tried NOT using mulch, but that did not help. • I have heard from MANY sources that marigolds will repel squash bugs. As far as I can tell, squash bugs are completely unfazed by marigolds. I planted marigolds around the outside of my entire garden, and planted them all around and amongst the squash plants. TOTALLY INEFFECTIVE. I will say that there are many varieties of marigolds, and I have not tried them all. I think this remedy is a waste of your time, unless someone can tell you exactly which type of marigold repels squash bugs (and even then, I would be skeptical). I still have marigolds in my garden just because my family likes them. • I've been told that using cedar wood chips as a mulch around the plant will repel squash bugs and keep them away. This was also totally ineffective. • I have tried tying the squash vines to a wire fence (to get the leaves and vines off of the ground). Unlike cucumbers and other vining plants, the squash vines are just too heavy and cumbersome for this to work well. I'm not sure it would help even if I COULD get the plants to grow on a fence, or that it would be good for the plant. • I have tried forcing the plants to grow inside a tomato cage, again to try and keep the leaves and vines off of the ground. This did make it a little easier for me to find/see the bugs, but I'm not sure it was really healthy for the plant, and I still lost most of my plants before they produced a single squash. I have to declare this solution a total failure as well. • I have tried crop rotation--planting the squash in a different location in the garden each year. Totally ineffective against squash bugs (although still a good idea, in general). • I have tried skipping growing squash for a year. Squash bugs reappeared as soon as I started planting squash again. • I have tried REDUCING the number of plants to just a few, so that I could more easily manage checking for bugs on a daily basis. I just could not catch enough of them soon enough to prevent damage and death of the plants. I sometimes could not check every single day. • I always remove and burn the dead squash plants immediately when they die. Still a good idea, even though it has never helped my squash bug problem.
<span>Franko</span> Tue, 07/17/2018 - 12:28
Vance, I am so glad someone said this - these home remedies make people feel good and are repeated endlessly on forums, but unless you have just one or two sickly squash plants, the idea of picking off eggs and adults is absolutely ludicrous. A single healthy squash plant will spread for 6 or 8 feet and have hundreds of leaves. I can find eggs anywhere I look. It would take hours to go over all the leaves and the adults would probably lay them faster than I could find them all. And I have not seen a single adult yet - they hide very well. I started using Ortho Max L&G Insect Killer with bifenthrin a couple of years ago and it is the solution for me (new product seems to be BubBGone Insect Killer). Sevin sounds good but does not work. I hate using chemicals in the garden but I am tired of growing winter squash and having it all eaten up by squash bugs, and the plants get sicker and sicker by late summer if not treated. I have grown more and more as you suggest, but I get few good squash by late Fall and hundreds of pounds of damaged ones. I feel spraying early in the season will kill squash bugs and borers and leave little residue by Fall when I harvest. My two cents!