How To Get Rid of Squash Beetles?

Written by Heather Ross
Updated: October 25, 2023
Share on:

Advertisement


Key Points:

  • The squash beetle looks similar to a ladybug. It is larger than the ladybug, however, and is yellow or orange in hue.
  • Squash beetles eat squash and pumpkin plants, which can become a problem if you’re garden becomes infested.
  • Early detection is the best way to get rid of squash beetles. Regularly check the underside of leaves and stems for oval-shaped, yellow eggs. Immediately remove them.

The squash beetle (Epilachna borealis) is an agricultural pest that naturally lives in the eastern United States. These insects are closely related to the southern squash lady beetle and the Mexican bean beetle, both of which look very similar. Some of their favorite habitats include gardens and farms. Using their sharp piercing mouthparts, their diet consists mainly of the leaves from squash and pumpkin plants, which can cause some minor economic damage every season (though not as bad as many other pests). Most of this damage is done to younger plants; older plants generally have the power to resist them.

This article will cover some important facts about the identification, prevention, and treatment of a squash beetle infestation.

How to Identify the Squash Beetle

Squash Beetle, Epilachna borealis on a leaf.
Squash Beetle, Epilachna borealis on a leaf. Squash beetles are easily taken for a ladybug, as their coloring is very similar.

©Huw Penson/Shutterstock.com

By learning some basic facts about the squash beetles, you can more easily identify a potential infestation. These insects pass through four distinct life stages, each one different from the last. After mating, the female lays masses of 30 to 50 bright yellow bullet-shaped eggs on the underside of the leaf so the larvae will have an immediate source of food to consume. These eggs are fortunately large enough in size to be fairly conspicuous to the naked eye, which should help with identifying them.

Within a few days, the larvae will begin to hatch from the eggs and then feed voraciously. The larvae of the squash beetle look like small yellow ovals with long dark spines emerging from their backs. Once it has grown sufficiently, the larva will begin the metamorphosis into adults. This pupa stage, as it’s called, hangs immobilized from a secluded spot, but it isn’t completely defenseless. It will secrete oily droplets at the tip of the hairs to deter ants and other predators.

Once it has fully grown, the adult squash beetle is characterized by a yellow or orange oval-shaped body (measuring about half an inch in size) with a big rounded back. It has seven large black spots on each wing casing and four smaller black spots on the neck area. When the wing cases are lifted up, the beetle is capable of full flight. The adult bug seeks out sheltered or secluded places to survive for the winter, including rocks, buildings, and plant debris. When they emerge in the spring, squash beetles will find a suitable host plant near their original habitat to mate and lay their eggs once again to begin the cycle anew. One generation is usually produced every single year.

Identification can be a little difficult from appearance alone because the squash beetles are easy to mistake for other types of insects. One of the insects they most strongly resemble is the ladybug. The main difference is that the squat beetle is generally larger in size and covered in an orange or yellow shell rather than a red one. Squash beetles only infest squash-like plants, whereas ladybugs are not considered to be agricultural pests at all; in fact, they feed on agricultural pests. Another type of insect for which it’s commonly mistaken is the squash bug. However, squash beetles and squash beetles are not closely related at all. The squash bug has a flat gray-colored body like a stink bug rather than the round yellow or orange appearance of the squash beetle. There is one significant similarity though: they do feed on squash and pumpkins just like the squash beetle.

Perhaps the best means of identification is to look for the signs of an infestation on your plants. Squash beetles prefer habitats where their host plants are naturally found. Their diet consists solely of the leaves from squash, pumpkin, and even sometimes melons and cucumbers, all of which belong to the cucurbits plant family. The larvae feed on the leaf tissue between the veins, while the adults tend to consume the main stems. Both generally chew semi-circular trenches from one edge to the other. They’re also found consuming the rind of pumpkins and squashes later in the growing season. The affected areas may look thin and darkened, but they rarely wilt and die. The good news is that they’re not aggressive defoliators and therefore rarely need aggressive measures to get rid of them.

In order to identify a potential infestation as early as possible, you should begin checking young plants every day in the spring and summer (paying particular attention to the underside of the leaves) for signs of egg masses or mating adults. This should hopefully allow you to catch them before they can cause significant damage to your plants. If you wait too long, then the infestation may grow quickly out of control. These insects generally move from their wintering sites outward to nearby plants and spread from there.

How to Get Rid of Squash Beetles

Get rid of squash beetles - marigolds
Big striped pumpkin on marigold flowers background. One way to deter squash beetles is to plant marigolds in your vegetable garden.

©Elena Seiryk/Shutterstock.com

Early detection is one of the most critical aspects of prevention. After your pumpkin and squash plants have grown, you should regularly check for signs of unprotected eggs attached to the underside of stems and leaves. Once you’ve found the eggs, you can easily detach them from the leaves and destroy them before they even have a chance to hatch. Larvae and adults are more mobile and generally harder to kill, but they are still vulnerable to most common pest control methods.

Squash beetles may take considerable time and effort to get rid of. Because they like to hide under plant debris, one of the most important steps is to properly clean up any debris lying on the ground to prevent them from easily hiding. Once the harvest season has been completed, you can work the soil again and remove any leftover foliage to deprive the larvae of a food source and prevent the new adults from naturally building up sufficient reserves for the winter. By the time autumn arrives, it might be too late to stop the previous infestation, but it can help to prevent another one during the next year.

Another excellent option is to collect the insects by hand and drop them into a bucket with some water and 1 or 2 tablespoons of dish soap. Noon is usually the best time to do this. The dish soap is highly effective at killing them, but this might be a time-consuming process; they are hard to catch and have a tendency to scatter once disturbed. An alternative is to create a homemade solution consisting of garlic clove, an onion, and cayenne, jalapeno, or habanero pepper mashed together and then covered with a quarter of water. After an hour of wait time, mix the solution with a tablespoon of dish soap and pour the liquid into a spray bottle. This solution should do some serious damage to squash beetles, but make sure to wear protective gloves and eye gear to prevent burning your skin and eyes.

Beyond these basic solutions, there are several other preventative measures you can take. You can place protective covers over the plants and vines until the blooming begins to prevent an infestation for as long as possible. Moreover, you might want to consider rotating crops every few years to prevent the insects from establishing a long-term foothold in your garden or field, but this solution may not be practical for everyone for economic reasons.

If you’re still struggling to control an infestation, then you might want to use pesticides as a last resort. However, because squash beetles aren’t terribly destructive, it might be unnecessary in most cases. If you do plan to use chemicals, then they should be applied early in the season, preferably at some point early in the morning or late at night. It should be sprayed directly beneath the leaves with enough pressure to ensure it will penetrate deep beyond the surface. It’s a good idea to read up on some basic facts about the insecticide first. Always buy an EPA-approved insecticide and follow the instructions on the label to prevent wider contamination or damage to your plants. Some chemical ingredients are more effective against squash beetles than others.

There is a good chance that no single solution will be completely effective, so you might want to pursue several of these strategies all at the same time. And fortunately, many of these solutions will work on other agricultural pests such as squash bugs as well.

Does Dawn Soap Kill Squash Bugs?

While there have been reports of using dish soap to suffocate squash bugs, it’s essential to be cautious as dish soap can potentially harm your plants. A more effective approach to utilizing soap for controlling squash bugs is to dilute it with water and create a solution.

This solution can be used to submerge and drown squash bugs that you manually pick off the plants.

To use this method of prevention, you need a spoon, an empty container made of plastic or glass, water, and a small amount of dishwashing liquid. Simply use the curved part of the spoon to gently scrape the eggs off the leaves, and then place them into the soapy water.

What Are Some Plants That Repel the Squash Beetle?

There are several types of plants that repel squash beetles because of their smells or their natural oils, including catnip, marigold, radish, petunias, and nasturtiums. These plants should provide an organic way to deter them from consuming their normal diet without the use of dangerous chemicals. However, all of the plants that repel the squash beetles do take up plenty of space that could be reserved for other crops, so it might not be a good option if you need that extra crop space for economic reasons.

The photo featured at the top of this post is © Huw Penson/Shutterstock.com


Share on:
About the Author

Heather Ross is a secondary English teacher and mother of 2 humans, 2 tuxedo cats, and a golden doodle. In between taking the kids to soccer practice and grading papers, she enjoys reading and writing about all the animals!

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.