Squash Bugs & Vine Borers

 Two Very Determined & Very Serious Pests

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

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.

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

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 are 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.

Once the eggs hatch, the larvae will 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.

There are a couple of other control methods you might come across when researching these pests:

• 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…

• The other thing you will see is injecting Bacillus thuringiensis (Bt) into the stem after the larva has entered. 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, you have to get the Bt in the right spot, and it usually takes 2–3 days for it to be fully effective. While the product claims to cause the larva 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.

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.

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 🌱