Don’t let the name “Squash” bug fool ya! Squash beetles can do horrible damage to a number of plants. They can devastate crops of summer and winter squashes, as well as watermelons, cucumbers, and cantaloupe.
While squash bug can be a nuisance in the garden, with the right prevention and control measures, they don't have to completely ruin your harvest.
This article will give you the knowledge to prevent and get rid of them.
What are Squash Beetles?
Their scientific name is Anasa tristis and they are common throughout the US but especially prolific in the southeast. They literally suck the juices from the stems and leaves of the plants. In some cases, they also chew the fruits.
Squash bugs can cause serious damage to crops if left unchecked, as they can quickly infest an entire garden. Once they hit the adult stage they are quite difficult to manage.
Signs of squash beetle damage include yellowing leaves, stunted growth, and wilting plants. They can cause young plants to wilt and die.
Adult squash bug. The good news is they are easy to see.
Photo credit: Beatriz Moisset
Cucurbit Yellow Vine Disease
If that weren’t bad enough they spread a disease called cucurbit yellow vine disease which is a bacteria. This disease can quickly kill your plants.
The symptoms of cucurbit yellow vine disease include wilting of the vines, yellowing of leaves, and stunting of plant growth. Affected plants may also have a reduced yield or produce misshapen fruit.
Squash bug nymphs (Anasa tristis) on yellow summer squash plant. Photo credit: Pollinator
Natural Predators of Squash Bugs
Luckily there are some natural predators to squash bugs. Some are beneficial insects. By encouraging these natural predators to thrive in your garden, you can help control squash beetle populations without resorting to harmful pesticides.
Here's a list of some natural predators of squash bugs.
Tachinid flies: These parasitic flies lay their eggs on the squash beetle larvae. Once hatched, the fly larvae will feed on the beetle larvae, killing them. They do not harm people or plants - just bugs!
Praying mantises: These insects are also natural predators of squash beetles. They will eat both the adult beetles and the larvae.
Praying mantises can be purchased online and make a great science project.
Spined soldier bugs: These predatory insects feed on various pests, including squash beetles. They are known to eat both the larvae and adult beetles.
Birds: Many bird species, such as chickens, ducks, and guinea fowl, feed on squash beetles and other garden pests. I think they prefer the larvae stage and I have allowed my chickens in the garden when I’ve had a particularly bad infestation (supervised of course!).
You can encourage the presence of wild birds in your garden by setting up bird feeders or birdhouses. Read my article on how to choose the right birdfeeder.
Toads: The American toad eats squash bugs as well as numerous other garden pests. Draw them to your garden with a toad abode. Read my article on FROGSCAPING: CREATE A FROG FRIENDLY BACKYARD HABITAT
Eggs on underside of squash plant's leaf. Photo credit Beatriz Moisset
Organic control Methods
If a squash bug infestation is already present, there are a few different methods you can try to get rid of them. One option is to simply pick the beetles off the plants by hand and drop them into a container of soapy water.
Organic insecticides: There are several organic insecticides available that can be used to control squash beetles. Some popular options include neem oil, and insecticidal soap.
Safer insecticidal Soap will work when they are young but less so on adults.
Neem oil does well at the nymph stage but again has little impact on adults.
Handpicking: Carefully inspect your plants daily and remove any beetles or eggs you find. You can squish the eggs with your thumb - a tad gross but it gets the job done.
Placing a bucket of soapy water below your plants and knocking off any beetles into the bucket can also be effective.
Companion planting: Planting strong-smelling herbs and flowers such as marigolds, garlic, and tansy near your squash plants can drive away beetles. These plants also attract beneficial insects like ladybugs and lacewings that eat beetle eggs and larvae.
Row covers: Covering your squash plants with lightweight fabric can physically prevent beetles from accessing your plants. Remember to remove the fabric when your plant flowers.
Great Soil - have fertile soil rich in compost and beneficial microbes will help to keep your plants healthy. Check out my article on Compost 101
Check out my YouTube video
Will Dish Soap Get Rid of Squash Bugs?
Dish soap can disrupt the cell membranes of squash bugs, causing them to suffocate and die. However, the soap may only kill adult bugs and not their eggs or nymphs (young bugs).
Using dish soap also requires careful application. A solution of one to two tablespoons of dish soap per gallon of water can be sprayed directly onto squash bugs using a spray bottle.
However, care must be taken to avoid damaging the leaves of the plant by adding just the right amount of soap - not too much that it burns the plant, and not too little that it doesn't kill the bugs.
Furthermore, washing off all the soap solution becomes important to avoid any damage it might cause to the plant in the longer run. So, while dish soap may help reduce a squash bug infestation, it should be used in conjunction with other pest management techniques.
How To Prevent Squash Bugs From Overwintering
Squash bugs overwinter in your garden soil and especially like garden debris. They will also shelter under dead leaves, boards, and even in sheds.
1. Fall clean-up
Squash bugs seek shelter in plant debris and other decaying materials during the winter months. To prevent overwintering, it is important to do a thorough fall clean-up of all garden beds. Remove all dead and decaying plant material, including vines, leaves, and fruit, and dispose of them away from the garden area.
2. Crop rotation
Crop rotation is another effective way to prevent squash bugs from overwintering. Do not plant pumpkins, squash, or zucchini in the same area where these crops were grown the previous year. Squash bugs overwinter in the soil, and by rotating your crops, you reduce the risk of these pests returning year after year.
3. Till the soil
Tilling the soil in the fall can help disrupt the squash bug's over-winter habitat. Plowing the soil can expose hiding pests to cold temperatures and predators, reducing the number of squash bugs that survive the winter.
4. Mulch
Using mulch in your garden can help reduce the likelihood of squash bugs over wintering. Apply a layer of organic mulch, such as straw or shredded leaves, around your plants. This creates a barrier between the soil and the pests, making it difficult for them to burrow down and survive the winter.
You may think because your yard gets only partial sun and has a lot of shade that you can’t grow vegetables or herbs. You are in luck! Many vegetables such as greens and root crops grow well in part shade.