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Squash Bugs: How To Identify, Treat & Prevent An Infestation

Squash are some of the easiest vegetables to grow in your garden each year. Whether you love the light, tender taste of summer squash like zucchini or you prefer the heartier fare of soups and pies made with winter squash like pumpkins, most of us make room for at least one variety of squash in our gardens each year.

But even if they are easy to grow, they’re still susceptible to a few diseases and pests that target squash, like powdery mildew.

Today we’re going to tackle a common squash pest – the squash bug.

Adult squash bug

The Anasa tristis; such a lovely name for such a hungry bug. These sneaky insects don’t discriminate and enjoy all manner of squash in your garden, from your heirloom Italian zucchini to the Connecticut field pumpkins you’re growing for Halloween. On rare occasions, you’ll even find them munching on cucumbers and melons.

Let’s take a peek under the leaves and learn how to manage squash bugs when they find their way into our gardens.

The squash bug is mainly found in North America, where it shows up each summer as an adult bug having wintered over somewhere in your backyard. Come June through July they begin to seek out squash for food and as a nursery for the next generation.

Oddly enough, their presence has grown over the last decade or so due to the increase in organic gardening techniques and the disuse of certain pesticides. Where once before they weren’t necessarily a problem, their sheer numbers now can wreak havoc on your squash.

And boy, are they prolific.

If you thought your zucchini produced a lot of fruit, hold onto your trowel because a single female squash bug can lay up to 250 eggs.

Squash bug eggs with female

Once they hatch, these bugs go through five separate moltings before reaching adulthood. The insects have dark, black heads and backs with bright, leaf-green bodies when first hatched. They become more elongated and darker in color with each successive molt, moving from gray to their final brown.

Nymphs just hatched

Adult squash bugs are about half an inch long and have a visible X shape formed by their wings on their back.

How to Spot Squash Bugs

Squash bug nymphs on leaves

These shy creatures will generally flee to the underside of leaves or hide in cracks in the soil if discovered. If you’ve got the beginnings of an infestation, you may find groups of young green nymphs huddling together on the undersides of squash leaves.

Squash bug eggs beneath leaves

Another tell-tale sign of the presence of squash bugs is their eggs, which are generally found on the underside of the leaves. The eggs can vary from yellow to copperish-brown, depending on their age.

One of the easiest ways to spot an infestation is by the damage squash bugs leave behind.

Squash bugs feed on squash vines, leaves and the fruit by piercing them with a tiny mouthpart, a bit like a straw, and then suck the sap from the plant. This feeding leaves behind tiny yellow pinpricks that will eventually turn brown.

Squash Bug Damage

Squash leaf with squash bug damage

If there are enough bugs, they can cause the plant to wilt, and the sites where the insects have been feeding can turn black and die. Many gardeners mistake this wilting and blackening for bacterial wilt.

While a few squash bugs can be annoying, it takes a lot of them to do enough damage to a mature plant to kill it. However, they can cause enough damage to kill young plants in great numbers.

Cucurbit Yellow Vine Disease

The squash bug is also responsible for the rise of cucurbit yellow vine disease here in the states. This once rare disease is now quite prevalent. Cucurbit yellow vine disease is caused by a bacteria (Serratia marcescens) transmitted through the sucking mouthparts of the squash bug. Within a few days of infection, the plant’s vines will turn yellow, and about two weeks from infection, the plant will die.

6 Ways To Deal With Squash Bugs in Your Garden

Squash bug on leaf

1. Plank Trap

One of the most effective methods of dealing with an infestation is also one of the simplest. (It’s also an easy way to see if you have squash bugs.)

Lay down planks in between the rows near your squash plants. A 2×8 or 2×10 works great. Lay the piece of lumber down in your garden near your squash plants, then early the next morning, shortly after sunrise, flip the plank over.

If you have squash bugs, they will be hiding under the piece of wood. Bring along a bowl of soapy water, and you can pick up the bugs and drop them in the water to drown.

2. Hand Pick

Handpick squash bugs off plants that you can see while weeding or picking squash. The smaller nymphs like to huddle together on the undersides of leaves. You can often wipe them out in these groups with a firm smoosh from your garden glove.

3. Pesticides

Unfortunately, some of the most effective controls for squash bugs are chemical pesticides which are also highly damaging to pollinator populations.

Organic growers looking to avoid using these options have their work cut out for them but can still control squash bugs in their gardens by using pyrethrin and neem oil. Only spray the plants in the evenings while the flowers are closed to avoid disrupting pollinators

4. Skip the Mulch

woman mulching squash plants

Squash bugs love to hide, so using mulch on or near your squash plants gives them the perfect place to hide. You may wish to skip mulching your squash plants if you have trouble with squash bugs. If you’ve already laid down mulch, consider raking it up to remove the insect’s hiding spot.

5. Use Row Covers in the Spring

Squash covered with row covers

You can prevent damage to young plants and take away female squash bugs’ nesting sites by using floating row covers in the early spring. Wait until your squash plant is well established before removing the row covers.

6. Trap Crop

blue hubbard squash

Because squash bugs are partial to certain species of squash, you can plant blue hubbard squash as a trap crop. It’s best to plant it well away from your garden if you intend for it to be a trap crop.

An Ounce of Prevention is Worth Ten Pounds of Squash

One of the best ways to deal with squash bugs is to prevent them from returning the following season.

As adult bugs will winter over in dead foliage, you should always remove your squash plants when closing up your garden for the year. There are quite a few pests that like to find shelter in last year’s plants, so you’ll be protecting next spring’s garden not only from squash bugs.

It’s also a good idea to begin searching for squash bug eggs early in the season, starting at the beginning of June. Check the undersides of the leaves of young plants for eggs and destroy the eggs by smashing them.

I’m a huge advocate for no-dig gardening; however, if you have an especially bad infestation of squash bugs, it may be advisable to till the ground in the fall. It will prevent the current generation of bugs from wintering over in the soil.

With these preventative measures, you can ensure that any issues you have with squash bugs this season will not be repeated next year.

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Tracey Besemer

Hey there, my name is Tracey. I’m the editor-in-chief here at Rural Sprout.

Many of our readers already know me from our popular Sunday newsletters. (You are signed up for our newsletters, right?) Each Sunday, I send a friendly missive from my neck of the woods in Pennsylvania. It’s a bit like sitting on the front porch with a friend, discussing our gardens over a cup of tea.

Originally from upstate NY, I’m now an honorary Pennsylvanian, having lived here for the past 18 years.

I grew up spending weekends on my dad’s off-the-grid homestead, where I spent much of my childhood roaming the woods and getting my hands dirty.

I learned how to do things most little kids haven’t done in over a century.

Whether it was pressing apples in the fall for homemade cider, trudging through the early spring snows of upstate NY to tap trees for maple syrup, or canning everything that grew in the garden in the summer - there were always new adventures with each season.

As an adult, I continue to draw on the skills I learned as a kid. I love my Wi-Fi and knowing pizza is only a phone call away. And I’m okay with never revisiting the adventure that is using an outhouse in the middle of January.

These days, I tend to be almost a homesteader.

I take an eclectic approach to homesteading, utilizing modern convenience where I want and choosing the rustic ways of my childhood as they suit me.

I’m a firm believer in self-sufficiency, no matter where you live, and the power and pride that comes from doing something for yourself.

I’ve always had a garden, even when the only space available was the roof of my apartment building. I’ve been knitting since age seven, and I spin and dye my own wool as well. If you can ferment it, it’s probably in my pantry or on my kitchen counter. And I can’t go more than a few days without a trip into the woods looking for mushrooms, edible plants, or the sound of the wind in the trees.

You can follow my personal (crazy) homesteading adventures on Almost a Homesteader and Instagram as @aahomesteader.

Peace, love, and dirt under your nails,