An abundant crop of squash, zucchini, and cucumbers is a delicious reward for your hard gardening work, but if squash bugs find their way into your garden, your plants could wither away before they ever bear fruit.
Squash bugs are highly destructive and hard to get rid of as adults, but even large infestations can be brought under control with the right approach. Even better, harsh chemicals are rarely necessary.
Identify the Culprit
Squash bugs are often mistaken for stink bugs and spined soldier bugs thanks to their similar shape. Soldier bugs are harmless and stink bugs require a different treatment approach, so it’s important to know which insect you’re dealing with.
Squash bugs are found only on plants in the Cucurbita genus. They’re most easily recognized by the pronounced points at their shoulders and the dark brown, nearly black spot at the base of their back when their wings are folded. Turning the insect over reveals orange or orange-brown stripes on its abdomen. Like stink bugs, when crushed or found in large numbers, squash bugs give off an unpleasant pungent odor often described as similar to cilantro.
In the early spring, squash bugs lay 1/16-inch light brown or reddish eggs in clusters of 20 to 40 along the veins on the undersides of leaves or on stems. After a week or two, these hatch into spider-like nymphs with white or green bodies and black legs.
Stamp Out Those Squash Bugs
If only a few of your plants are affected, the easiest way to get rid of the bugs is to hand pick them from the plants. Bring a bucket of soapy water out with you and drop in any adults, nymphs or eggs you find.
To make the process easier, lay boards or shingles on the ground under the affected plants. The bugs will shelter under these during the night so you can remove them in the morning. You’ll still need to inspect your plants for nymphs and eggs, though.
Diatomaceous earth, a natural product that’s harmless to people, pets, and plants, can also control with minor infestations. Just sprinkle it on and around any affected plants.
For more advanced infestations, you might need to apply a pesticide to see any real improvement. Careful application is a must, though, because these insects are often hidden on the undersides of leaves and near the crown (base) of the plant. You’ll need to make sure you reach these areas when you spray the insecticide.
Neem oil, a natural pesticide that comes from the neem tree, is known to be effective against squash bugs. It’s safe for people and pets as well as honeybees and other beneficial insects.
You can buy pure neem oil or choose a commercial insecticide made with this oil. You’ll typically need to apply the product two or three times at intervals of seven to 10 days, but always follow the directions on the product’s label.
Insecticides containing carbaryl are another option, but they should be a last resort because this chemical is toxic and kills beneficial insects. Carbaryl products work best if applied when the eggs are hatching, so you may need to reapply two or three times.
If you want to try biological control of your squash bugs, the tachinid fly (Trichopoda pennipes) can help. This orange fly lays its eggs on squash bugs, decreasing the bugs’ lifespan and ability to reproduce. They won’t always clear up a squash bug infestation, though, because squash bugs carrying fly eggs can still live long enough to reproduce
Prevent Future Squash Bug Infestations
Squash bugs produce only one generation each year in cold-winter climates or two in warm climates, so if you can keep them at bay for spring, you stand a good chance of avoiding any issues for the rest of the growing season. Start by installing floating row covers over seedlings and leaving them up until the vines start to blossom and need pollination. More mature plants are better able to resist squash bug damage.
If you have a long growing season, consider delaying planting until early summer when the bugs have finished laying their eggs.
Throughout the spring, inspect your plants for squash bug eggs at least once a week. It takes just 10 days for the eggs to hatch, so don’t wait too long between inspections.
At the end of the growing season, clean up your vegetable patch to reduce the number of places adult squash bugs can spend the winter lying in wait for your spring crops. Burn or compost dead squash vines, and plow under any remains of the plants left in the soil. Removing any other debris, such as dead stalks and leaves will help, too.
With good planning before you plant, you’ll have an even lower risk of squash bug problems. Choose squash varieties that are resistant to squash bugs, such as Butternut, Royal Acorn, and Sweet Cheese. Rotate your crops and avoid planting plants in the Cucurbita genus in the same place two years in a row.
Enjoy the benefits of companion planting by planting nasturtium and tansy around your Cucurbita plants. Train vining plants on a trellis to make them less appealing to squash bugs.
While squash bugs have the potential to wreak havoc, keeping your plants safe is really just a matter of staying one step ahead of these bugs. If squash bugs are common in your area, plan ahead before you plant. Even after the bugs have moved in, though, you can still get rid of them using natural methods such as hand removal or neem oil application.