If you’ve ever grown pumpkins, you’ve probably seen squash bugs crawling around in your garden. They’re one of the most common pests for cucurbits. Whether it’s zucchini, pumpkins, butternut, melons, or cucumbers, squash bugs love infesting squash gardens.
The squash bug looks a lot like a common stinkbug. When I first saw squash bugs on my early pumpkin plants, I assumed they were just stink bugs.
But as the numbers increased, I began to worry. A little research proved I had a bigger problem – a squash bug infestation on my beautiful, heirloom pumpkins!
What Are Squash Bugs?
Squash bugs (Anasa tristis) share a lot of characteristics with stink bugs. They’re both gray, hard-bodied, beetle-type bugs. Many people say that squash bugs also “stink” when crushed. But squash bugs have a flatter, narrower body, while stink bugs look decidedly rounded.
Stink bugs also prefer to attack tomato and bean plants, while you’ll rarely find squash bugs far from the pumpkin patch.
The adult squash bug’s oval body is rarely over a half-inch long. But for a little fellow, this pest can cause a lot of damage.
Squash bugs suck out the sap from plants in the cucurbit family: squash, cucumbers, and melons. Adults can also feed on the fruit of these plants – but unless you have an extreme infestation, it’s rare to lose healthy plants to squash bugs.
The Life Cycle of Squash Bug
Adult squash bugs generally overwinter in or near the garden. They cuddle up under dried leaves, dead plants, or other garden clutter until spring warms the soil. Then, when your cucurbit seedlings are springing up in the garden, adult bugs mate and lay their eggs.
Squash bugs usually lay their eggs on the underside of squash leaves. Occasionally you will find the eggs on top of the leaves as well.
Squash bug eggs are small, dark, and hard-shelled. They look like little brown seeds. Squash bug seeds hatch in about 10 days, so if you find them, remove them right away – before the nymphs emerge.
Squash bug nymphs look very similar to the adults. They’re small, gray insects that swarm all over cucurbits. Both adult and nymph squash bugs feed on the leaves and stems of cucurbit plants. But nymphs have a softer body.
By the time you notice squash bugs on your plants, they’re often adults. While adults are harder to kill, you can manage them when you find them on your plants. Adult squash bugs tend to congregate in groups on squash and pumpkins.
Because they aren’t solitary creatures, it’s easier to pluck them off the plant and destroy them.
Signs of a Squash Bug Infestation
Of course, it’s easy to know that you have a problem when you see bugs on your plants. But that isn’t always a reliable way to figure it out.
When squash bugs attack your plants, they can cause a lot of damage. Look for wilted leaves, yellow spots that eventually turn brown as the sap is sucked up from within them, and ragged holes in your squash leaves.
These are the clearest signs that you’ve got a squash bug problem in your garden.
Controlling Squash Bugs
Squash bug control has three stages. If you spend time controlling squash bugs early on, you’ll have fewer bugs to deal with later in the season.
Squash bugs mate and lay their eggs early in the summer. Expect to find eggs on the underside of cucurbit leaves in early to mid-June. When you see scattered clusters of brown seedlike eggs, scrape them off the leave and into a bucket.
I like to collect all the eggs I can find and then feed them to my chickens, but other gardeners drown them with a little kerosene or oil. You can also use water mixed with dishwashing liquid.
The point is to get rid of as many eggs as possible before they hatch. Once hatched, squash bugs are a lot more mobile and destructive.
While they’re immobile on the leaf, gather up as many as possible to prevent a mass hatching. Most of the time, squash bug eggs are on the underside of cucurbit leaves, but don’t be surprised to see them on the top side of leaves as well.
Check for eggs on a weekly basis throughout late May and early June. Remove eggs as you find them. It’s likely you’ll miss a few clusters of eggs, but most of the pests will never see the light of day.
Controlling squash bug nymphs is a little more challenging than egg control. Nymphs are mobile. They’re also hungry. The nymphs devour squash leaves by sucking the juices out. They can also feed on tender, young squashes and melons.
Once squash bugs begin hatching, walk through the garden with a jar and lid. Pluck the young pests from their buffet and bottle them up.
Chickens are less excited about the nymphs than they are about the eggs. It may be because of the decidedly stink-bug flavor of these pests. When I gather squash bug nymphs, I just drown them in soapy water in a lidded jar. But there are other options.
Many people catch both nymph and adult bugs by setting out a wooden board in the garden at night. Squash bugs congregate under the wooden board to enjoy the residual heat throughout the night.
In the early morning, go out the to garden, and collect the board. Then, you can smash the bugs on the board between two hard surfaces.
Neem oil and horticultural oil are effective on the nymphs. If you decided to use these natural insecticides, spray them on the undersides of the leaves morning and evening (or as the manufacturer recommends).
If you use them consistently, along with other preventative measures, you should be able to kill off most of the nymphs before they reach adulthood.
Insecticides – both organic and conventional – are almost completely useless against adult squash bugs. Adults are hardy creatures with nerves of steel and a tough exoskeleton.
If you’ve waited too long to address your squash-bug problem – as I did last year – then you’ve got to collect these tough, nimble bugs and drown them in something like kerosene, used motor oil, or water mixed with dish soap.
Of course, you can collect them on a board at night, just as you did with the nymphs, but adult bugs are a bit harder to smash. Be ready to collect the survivors and try again as soon as you lift up the board.
Some gardeners go through their squash vines with scissors each morning and manually cut each insect in half. It’s tedious, repellent work, but it does reduce the number of bugs in the garden.
If squashing, slicing, and drowning aren’t your favorite garden activities (and they really shouldn’t be, let’s be honest) – deal with your squash bugs as early as possible.
Squash Bug Prevention
After one season spent battling squash bugs, I was all set for life. When autumn came, I took steps to make my garden as inhospitable as possible to these invading insects. Fortunately, prevention is similar to many other pest-prevention measures.
Clean up the garden. Putting your garden to bed for the winter makes springtime planting prep easier. It also denies overwintering space to a host of invasive bugs. Squash bugs spend the cold season hiding under leaves, dead plants, and debris.
Remove all that clutter before winter so these insects have nowhere cozy to hide during the cold season.
Practice crop rotation. Don’t grow cucurbit family plants in the same spot two years in a row. Move your plants and replace them with tomatoes or peppers. Crop rotation makes sure that when your flock of squash bugs wakes up from their long winter naps, they’ll be farther from the squash plants they love.
Plant squash bug-repellent companion plants.
Nasturtiums, thyme, catnip, and alliums are all naturally repellent to squash bugs. Of course, planting these companions alongside your squashes won’t drive away these pests entirely, but it will encourage the pests to look elsewhere for sustenance.
If you’re not having a lot of luck keeping these insects out of your garden, plant squash bug-resistant varieties. There are a few cultivars and species of cucurbit family crops that are resistant to A. tristis.
These plants just don’t taste good to squash bugs. They have no interest in eating them, so they quickly move on to greener gardens.
Try planting ‘Waltham’ butternut, ‘Blue Hubbard,’ ‘Improved Green Hubbard,’ ‘Smooth Criminal’ summer squash, ‘Early Summer’ crookneck, ‘Royal Acorn,’ ‘Long Island Cheese’ pumpkin, and any butternut squash.