Squash Bugs & Vine Borers

 Two Very Determined & Very Serious Pests

🪲 Garden Pests | by Guy Saldiveri | March 4, 2026

Squash Vine Borer

These are without a doubt the most serious foes I deal with in my garden. The squash bug and the squash vine borer deliver more damage pound-for-pound—or is that ounce-per-ounce—than any other pest I have ever dealt with. The vine borer is by far the worst of the two. 

Some of my favorite things to grow are winter squash, zucchini, and pumpkins. These two pests just love to wait—or it seems so—until the plants are full, healthy, and producing fruit. 

They’ll attack and can kill a plant within three or four days—at least the SVB can—if you’re not on your toes.

Squash Bug

These two pests are both serious, but they attack in very different ways. 

Squash Bugs

The squash bug will pierce the vine stem and suck the sap. While there are many other bugs that do the same, squash bugs are usually present in high numbers, and they’re much more voracious. They can easily cause an entire vine to wilt quickly and die off. 

Your best bet is to locate and destroy the eggs if possible. 

Squash Bug Eggs On Leaf

Flip over the leaves and look for those bronze-colored, football-shaped eggs. They'll usually be tucked right into the V-shaped ribs of the leaves. Use a piece of duct tape or squash them with your fingers to destroy them.

Once they hatch and get some size to them, they become incredibly fast and hard to catch, but they love to hide. 

The Cardboard Trap

You can try placing a sheet of cardboard down at the base of your plants. Leave it out overnight, and when you check it in the morning, you'll often find them hiding underneath. You can scrape them off into a bucket of soapy water or just step on them to "squash" them. 

Otherwise, you just handpick them like I recommend for the leaf-footed bugs. If you have a handheld vacuum, you can try that as well. Some folks swear by it.

Squash Vine Borer

Squash bugs are easy to see on the plant; squash vine borers, on the other hand, will lay eggs on the leaves or base of stems, then fly off. They're hardly noticed because they look very similar to a wasp and just blend in. They deposit their ammunition and fly off into the sunset. You only notice they were there AFTER the damage has been done—or at least well on its way.

Squash Vine Borer Eggs

Once the eggs hatch, the larvae immediately burrow down and try to make their way down toward the crown. They eat the plant from the inside and block all water and nutrient flow from that point out toward the end of the vine. Once inside, the larvae are difficult to kill because they're inside the vine. The only ways to get to them are by cutting the vine open and removing them, or by trying to pierce the vine with a pin and stabbing the worm until you kill it. 

Most of the time, I wind up doing the surgery method because you can never be sure where that little thing is. Hitting it is not the easiest thing to do. Cutting open the vine with a clean, sharp, X-Acto blade and fishing the larva out is the best way I've been able to keep them under control. 

Once done, the vine will heal on its own. Squash are truly amazing plants in this respect.

Other Control Methods You’ll See

Covering the base of the plant with foil or some other wrap: 

While this can prevent any borers that have overwintered in the soil from emerging and penetrating, my personal experience trends toward them attacking from all angles and heights. The sprawling vine up top is just as attractive to them as that main stem going into the ground. Remember, they lay eggs on leaves, the eggs hatch, the larvae feed.

Row covers and bug netting: 

I can't say anything bad about either one of these when it comes to function. They work extremely well for what they're designed to do. For my application? I'd be better off building a full-blown greenhouse — and here's why.

While row covers allow rain and light to pass, they also trap heat and humidity. That’s fine in cooler months, but in the heat of a Southern MS summer, it would cook my garden. 

Insect netting would be the next step, but that means building frames around trellises to keep at least a twelve‑inch air-gap between the vines and netting. Squash grow big, and they grow fast — they will easily close that air-gap. The protection only exists as long as separation exists. If a leaf touches the netting, the moth can land and lay eggs right through it — effort wasted.

Covers and netting also make it harder to harvest, weed, or even check plants — and don't forget pollination. Also, unless you set them up perfectly, you can’t be sure you haven’t trapped overwintered pests inside. For a small hoop house over a few zucchini, they make sense. For a setup like mine, it’s easier to scrap the idea and just go buy the squash.

Injecting Bacillus thuringiensis (Bt):

Some folks indicate this is very effective; I’ve found it to be more of a maybe‑at‑best method of killing them off. To start with, timing is crucial and you have to get the Bt in the right spot. Another thing is it usually takes 2–3 days for it to be fully effective. While the product claims to cause the larvae to stop feeding immediately, I've never had that experience. The 2–3 days to kill the larva is 2–3 days too many for me.

Spotting the Damage

Bottom line—if you notice your plants wilting, especially after just being watered, it’s time to start looking. SVB larvae will leave an open hole covered in brownish, sawdust-like excrement—called frass. 

Once you see this, you can be sure there’s a larva inside. I usually start having trouble with these two around the May–June timeframe. 

By then, my squash are large, thriving, putting out great fruit, and I would imagine a very strong odor. It's that odor that's luring these little-you-know-whats to the feast. And once they show up, the fun is over. It's time to really pay attention and keep on your toes. Either one will bring a plant down in a few days. Together, they will destroy your entire crop in no time.

Now I will add an interesting observation here: This year we had a late freeze that took out many of the blackberries and blueberries. I think it took out quite a few of the emerging borer moths as well. 

I also got off to a later start this year and wound up planting in late April and early May. I think the combination of the late freeze and late planting reduced the pressure I had this year and I've only had two instances where the borers dug into my plants. 

While we can't control the weather, we can definitely control when we plant… Just something to think about.

Your luck may vary, but I find that keeping a constant watch on the plants, performing larval surgery when needed, and succession planting are the best ways to ensure a good harvest.

If you grow squash, I know you're familiar with these guys. Drop me a comment and let me know how YOU deal with them.

Happy Gardening 🌱