Squash Vine Borer

How to Identify and Get Rid of Squash Vine Borers

Squash vine borer, by Massiv99: Wikimedia Commons


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Here are tips on how to identify, control, and get rid of the squash vine borer.

What are Squash Vine Borers?

It can be so disappointing when your squash is thriving and suddenly starts to wilt. The culprit is probably the squash vine borer. The plants wilt because larvae is boring within the lower part of the stems.

Squash vine borers attack squash, zucchini, pumpkins, and gourds. They prefer Hubbard squash and are not as fond of butternut squash. Cucumbers and melons are not usually an issue.

The borers overwinter in soil as pupae in cocoons. When the adult clearwing moths emerge in early to midsummer, they lay eggs singly or in small groups at the base of stems. The eggs will hatch within 1 to 2 weeks after being laid. The larvae will then bore into stems to feed for about 2 to 4 weeks; sometimes they may also bore into the fruit. In northern areas, there is one generation per year; in southern areas, there may be 2 generations.

If caught early, it's possible to save the plant. If caught after the eggs hatch, it may be too late. Controlling the squash vine borer is mainly about prevention.


How to Identify Squash Vine Borers

  • Eggs: The eggs are tiny, flat, oval, and brown. The eggs are laid scattered around the bases of squash and pumpkin plants. 
  • Larvae: If you slit open a stem lengthwise with a fine, sharp knife, you will see the borer larva, which has a fat, white, wrinkled body and brown head; it can grow to about an inch long.
  • Moth: The adult is a moth about ½ inch long that looks a bit like a wasp with a black body, marked with orange-red. The hind wings are transparent and the front wings are metallic green.


Photo Credit: University of Wisconsin-Extension. If you see the adult squash vine borer moth, beware that it is probably laying eggs!

Squash Vine Borer Damage

  • The leaves of the plant will probably start to wilt.
  • Look for holes at the base of the plant and green to orange-yellow sawdust-like frass (droppings).
  • Squash vine borers feed on the material inside the stems of the plants. The stem will rot at the site of the feeding.


Photo Credit: Donn Cooper, University of Georgia. Squash vine borer larvae can cause major damage to the inside of your squash plant stem.

Control and Prevention

How to Get Rid of Squash Vine Borers

  • If you catch them VERY early, you can manually remove the squash vine borer. Slit the lower stem lengthwise with a fine, sharp knife to remove the larva by hand. Gardeners can make a vertical slit in the stem with a sharp knife and manually remove the larvae. One plant can house several. Then cover the slit stem section with moist soil about the point of injury to promote formation of secondary roots. Also, extra rich soil near the vines helps rerooting.
  • Or, if you spot entrance holes and “sawdust,” try inserting a wire and thread through the stem for some distance to kill the inside larvae.
  • Sprinkle diatomaceous earth around the stalks when the squash vines are small. Reapply after rain. Also, build up the soil around the vines. Or, sprinkle black pepper around the plants as a defense.
  • If possible, catch and destroy the moths at twilight or in early morning when they are resting on the upper side of leaf bases.
  • There are insecticides, too, but timing is critical; they are effective when applied at the time that eggs are hatching. The biological insecticide B.t. (Dipel) can be injected into the squash stems, however, it is not usually effective because the larvae are protected inside the plant. Many find carbaryl (Sevin) to work. See your local garden store for advice on appropriate chemical controls. 
  • Trap the adult orange moths with yellow sticky traps and yellow-colored bowls of soapy water.
  • A trap crop of very early-planted Hubbard squash can be used to alleviate pest pressure on other squash.
  • Plant extra squash for the pests! They are around for 6 to 8 weeks and can only eat so much (or, so we think!).
  • An old folk remedy from The 1963 Old Farmer’s Almanac says that wood ashes were effective against the squash vine borer.


Photo Credit: Lee Jenkins, University of Missouri Extension. Larvae of the squash vine borer can destroy cucurbit stems if not controlled and prevented.

Prevent Squash Vine Borers

  • Sometimes the best solution is to start your squash as early as possible. This way you’ll be harvesting before the summer time when vine borers become active. If you plant early, you may need to be prepared to cover your plants in case of frosts.
  • Do not plant squash in the same bed two years in a row. Squash vine borers overwinter in cocoons in the soil. Also, clean up ALL debris and clean up your soil in the fall.
  • As soon as the squash is harvested, get rid of the vines. Till the soil in the fall and spring to get rid of overwintering pupae.
  • Preventative measures include covering the stems with a barrier, such as strips of nylon stockings or aluminum foil, to prevent egg laying. 
  • Importing parasitic wasps prior to the egg stage can be helpful as these wasps are the borers’ natural enemy.
  • One of the better solutions is to cover crops with floating row covers to prevent egg laying (but only if you are sure there aren’t pupae overwintering in the soil). You can also drape these row covers over frames. This will not only give you a head start over pests but protect your plants from strong heat and frost.
  • If you give up on zucchini, which is susceptive to vine borers, try growing a squash that’s more resistant such as Cucuzzi (Lagenaria siceraria), also known variously as the snake gourd; it’s pale green and twists and spirals like a snake.

Learn about the other main squash and zucchini predator: the squash bug.

Do you have any tips for controlling these pests? Let us know below!

Plants Affected

Reader Comments

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Squash borer.

According to the old farmer's almanac, what stage should we apply wood ashes and how do we apply it?

Wood Ash Ph

Yes, wood ash can affect soil Ph, sometimes for the better, sometimes not. It all depends on your soil so it is best to have it tested to determine if applying wood ash would be beneficial or harmful. We will try to get a pic up, but it is difficult to find any that are of the necessary size and quality. The eggs are tiny, flat, oval, and brown.

squash borer worms

I appreciated all the information and the way it was presented - both organic and inorganic.
Many options available. Next year I will try new soil (am a container gardener), laying down wood ash at the stem's base (anyone tried this yet since 1963? If so, what are the results?) wrapping vines with foil, hilling soil, then more wood ash. How will the addition of wood ash affect the ph of the soil? Any amendments to counter it necessary?

If possible - could you add a photograph of the eggs laid at the stems?

I believe you meant " try

I believe you meant " try growing a squash that’s *more* resistant such as Cucuzzi" (not less) :)
Thanks for this article! Very helpful!

Resistant Squash

Oops, thanks for catching that, Hannah! We really appreciate it, and we’re glad you’ve found the article helpful!

successful and easy control of squash vine borrers

I have looked over many sites dealing with Controls for squash Vine borer. With a heavy infestation of these moths I have fought to protect squash using nearly all the suggested methods. Some work(complete netting of the plants) but are very labor intensive. Finally I watched the moths in the garden for many hours (letting them do their nasty work without disturbing them) and realized that they are extremely sensitive and careful when laying (THIS IS THE KEY TO CONTROL!!!!!). I then developed a much Less labor intensive method that seems to work Exceptionally well. Chopping hay in 2 to 4 inch lengths I let the hay lightly fall over the stalks, particularly the base, and even onto fruit to form a very open matrix. The moths will not land and lay, it appears to prevent landing of the moths. It's possible to walk through the garden and drop fluffy handfuls of chopped hay over any exposed vines every few days quickly and efficiently, apparently completely discouraging the egg laying. This is an organic method(Obviously) and takes relatively little time in a small home garden. If this approach is used Diligently it is nearly 100% effective. Anyone using the technique needs to make just a matrix of hay, Very open and loose, LIGHTLY ALLOWED TO DROP OPENLY, A HAND FULL AT A TIME (no need to put a lot) but with small enough gaps so that the moth is discouraged. The moths DO NOT LIKE CLOSED AREAS, THEY WANT OPEN ACCESS TO STALKS AND FRUIT - AGAIN, THIS ISTHE KEY). You don't have to pack in the chopped straw, just scatter it with most pieces looking like open "pick up sticks", that seems to be all that's needed. If you experiment with this method you will find it EXTREMELY effective and efficient. I've tried to spread the word on many garden sites but have not been successful, please share the idea. Call it the Mayo technique!

I am trying "The Mayo

I am trying "The Mayo Technique" next year on my pumpkin vines! These stinking pests are a real problem in WV, and after many approaches to deter them, my pumpkins are a complete loss this summer...just ripped my vines out and bagged 'em up. Grrrrr. I used to grow 100 lbs pumkins in NE Ohio with no sign of them. Here's hoping it will help me to grow that one big pumpkin I'm dreaming of for my little girl! Thanks for the tip! :)

Squash Vine Borer, the Garden Pest from Hell

Squash Vine Borer, the Garden Pest from Hell
The Squash vine borer is the hardest pest to control in my garden. Excuse my seeming cynicism in these comments, because I am a little, No, a lot frustrated with failure year after year and the lack of effective methods and frankly some silly advice in much of the literature. These little worms have got our number. We can go to the Moon, and that was 45 years ago, and cure many cancers now but we cannot solve the borer problem. I have no agenda against the writer(s) of this article and sincerely hope whoever it is will not take my views personal. I am sure they are professional writer(s) and above any pettiness that might come from a disrespect of my views. The contents here include most all the common points found in the literature universe I am aware of. If the writer(s) do take issue you may never see this article or they might retaliate by correcting my spelling or grammar. If so, I have had it. They can only give you the material available. The best advice any have given up to now on this subject is of limited value if not total crap. If not clear by now, I have attempted to inject a little humor in what I say. If that is not obvious then I suck at something besides fighting vine borers.
This article is somewhat helpful but all stuff I have heard before. Reading this article, I noticed there are no photos of the eggs and little information on how to read the signs of their presence before the eggs get laid? Timing is going to vary by your climate and latitude. Being able to act early and knowing what to do is critical. This article could not be more correct on that point. They are spot on. So what er ya gonna do? Sounds like you best be doing the whole list, all the way up to everything short of making a moth voodoo doll. Will you have time to run the rest of your garden? Will you engage in an focused and intense battle with the borers only notice later it has been two weeks and everything else died form neglect.
No photo of the moth here either. I thought moths were those butterfly looking things that fly around the porch light in the summer. These things look more like a wasp. I have seen them before and I found it a moment of helpless feelings that either he/she or one of its nearby cousins has a plan to cause loss of my squash and anything else they might fancy. Trying to catch or trap the moth? Good luck with that one. I am sure you will get one here or there with the right trap. Stand around the plants at dusk and dawn and catch them lighting on the plants and kill them. How? A fly swatter or dish towel pop? Does LOL fit here? All it takes it one moth to lay eggs on every plant you have, unless you have a commercial crop then it might take two or three. Photos? I really think they would be helpful so you know what to look for so you know they are here/there…you know? You still might fail to stop them but you are not blindsided. Plant two crops, one early and another later, which is intended to be one for the worms and one for you? Ridiculous! Don't plant where the moth eggs might be in the ground. Hmm? The moth can fly, so zipping over to another spot in the garden a few feet away is not going to trouble him. Netting? Will work for the birds maybe. For the Moths? That is sort of goofy. It might serve to keep the worm in. These moths are tiny and can easily get around if not through netting. Netting with holes that small might impact vital sunlight the plant requires. Just one moth finding its way past the netting and oh well, you are in for it again. So, more than likely, netting is not a very effective method to stop them. My frustration, and I expect yours as well, is that all you get are these measures to take; that in aggregate, do not stop the problem. No pun intended but there are holes in about everything suggested. Maybe it slows them down a bit but what do you profit by taking all the measures when one moth in one day can lay enough eggs to destroy your crop. Even you mange to take out the locals there is a chance an outside hit-moth from the next door garden with show up. And, you if don't see the eggs in time, inside two weeks they have moved in and started on the buffet. Even if you see the eggs before they hatch, how do you get them off other than cut a hunk out of the stalk? What happens if you drop a few in the process? I wonder.
Once you see the hole and the frass/droppings they are in the stalk and the only hope you have is injecting Dipel BT liquid inside the stalk but it is hard to tell where to inject with your syringe. Plus it is hard to get to the base without breaking the plant. Unless careful, you will do more damage than the worms. slit the stalk, remove the worm and cover the cut with soil. Good for the one worm. What about the rest of the family further up? What about the idea of sticking a wire in the holes to attempt to skewer them? Samurai Gardner, Hieah! Well that might work sometimes. Often there are three and four of the worms in one plant and they are constantly moving. So bag one and the others to still get the job done. Once inside the stalk they will flatten the plant in a matter of days. Last year I started slitting one plant and by the time I finished the plant was shredded with cuts because you have to start at the hole and keep cutting until you find the little jerk. I would say giving one of these worms one day on your plant is enough to wilt it severely. There is really no one single best solution and I find that discouraging. The only absolute way to stop them is to not plant squash.
This year I have planted squash and again, I will do battle with these ugly little slim bags for the freedom to have squash on the table. Sadistic really but I want squash. I refuse to let a worm dictate my dietary choices. My plan, while not perfect, is to spray, spray, spray. I plan to mix liquid seven and Malathion a little stronger than recommended and spray the stalks from the ground up to as much as a foot and the ground around it 6-8 inches. Do not spray blooms is good advice offer in this article. Why spray the ground? I don't know. It makes me feel better. If the worm gets a taste of the poison and makes a run for it maybe he won't get far. I will spray once a week. More if it rains. I may try wrapping the stalk with foil but suspect that it will be hard to apply enough to cover everywhere they might lay eggs. Plus the moth could get behind foil enough to give the eggs a barrier from the poison. I may try foil anyway because it is reasonable prevention. I will watch for the holes in the stalk and inject BT into infested plants. I fully expect I will have some get in but hope I can have them check out early. I will inject high and plentiful until I see it running out of the entry hole.
After all of that is done, or maybe better if before, pray the poison spray works.
Billy Knight

I started my pumpkins in the

I started my pumpkins in the greenhouse until July 14th. Thought I was safe here in south Jersey. But no, I just caught two moths today, August 5th. Obviously, we have a second hatch here. Yuk....

I'm from Central NJ and

I'm from Central NJ and planted yellow crookneck squash in mid-July. I saw three adult squash borer moths on the plant in late July (managed to kill one). Today, I saw evidence that squash voter beetles have been damaging my squash plants. I pulled one out so far and am debating what to do with the other one. My garden has been a disaster this year, from downy mildew to wilt to being overrun with cucumber beetles to something killing all my pepper plants and now this. It is enough to make me think about giving up.

This is the first year that I

This is the first year that I didn't see a sign of Squash Vine Borers in my zucchini or acorn squash. I tried something different this year.
After they started to vine out pretty good I injected the stems with a Thuricide mixture. Then I started spraying the stems with Liquid Sevin, especially the lower stem where it comes out of the ground. As the vines got longer, I sprayed the main stem further away from the ground too. I sprayed every time after a good rain as well as once a week.
I figured, when the egg hatches and it starts to bore into the stem, it had to go through the Sevin, therefore, it would die before it got in the stem. Maybe it was just coincidence but I never saw a sign of borers. After the end of August I stopped spraying.
Don't spray the flowers with Sevin! It will kill the bees and other pollinators. I use Thuricide if I want to spray the whole plant to prevent bugs from eating the leaves.

Have you thought what all

Have you thought what all this spraying and injecting might do to what you eat?

I do not like to introduce

I do not like to introduce poisons into my soil as it kills beneficial organisms, and earthworms. You can wrap the stems with foil when the plant is young. I tried hilling the soil around the stem to prevent the moth from laying eggs there and so far it has worked on my winter squash. Then comes the squash bugs.

My pumpkin leaves began

My pumpkin leaves began wilting and fruit stopped growing. I saw the orange stuff coming out at the base of the stems, by the roots and saw holes so I figured bores. I took a blade to them this morning and cut out long, vertical sections out and found bores in every vine. All but one looks like it has been infected. I covered them with soil and watered heavily. We'll see what happens. I figured I either saved the plants or more likely killed them faster than they were already dying.

Well, we are going to get a

Well, we are going to get a total of 9 pumpkins from our 8 seeds planted. The borers definitely hurt our crop. After I cut them out, the vines kept growing for a while, producing a female here-and-there. They eventually starting dying, turning yellow and brown. They don't look pretty right now, but we did get some results. Most are pretty small though. I also had to deal with cucumber beetles and a lot of mildew due to the wet summer. All three problems occurred for our first year of growing. Hopefully next year will be easier.

this year I decided to try

this year I decided to try giant pumpkins again, not for competition just local fun. but when I was looking for something to spray or drench the pumpkins, they miss informed me about their product killing vine borers. wiped out one plant, finally tried some Malathion 57%. it actually says it kills vine borer. I had some success with injecting the spray with cattle syringe and large needles, it does kill the worm fore sure, but no way on knowing how many I missed. I will try the nematodes next spring. I use to use this professional spray called WARRIOR T OR Z, but unless u know a commercial friend sprayer its almost impossible to buy. its deadly and all the giant pumpkin growers use this. very pricy, but hey it works. just have to be carefull when u spray. in my area , we've had no bees for a few years because of aerial crop sprayers, this is the first year I've seen some in my patch. after my pumpkins are set that I want to keep, I cut off all the flowers to help keep the bees away.

IS there one source of

IS there one source of nematodes better than another? this will be a new and hopefully have great results using nematodes.

I have not had any problems

I have not had any problems with squash vine borers since I started using beneficial nematodes in the spring. Garden's Alive is the source I've used. They are called 'Grub Away Nematodes' - they are pricey but they work & should control the cornworms too. Unfortunately they do nothing for cucumber beetles!

Any good solid total kill

Any good solid total kill methods would be great to know, even if I need to wait till next year to replant. These pests (all 3 together) are killing everything I have growing!

The article is inaccurate.

The article is inaccurate. The eggs are laid on the OUTSIDE of the stem, singly, by the adult moth. They then hatch and burrow into the stem, where the larva grows. There are no egg masses in the stem, as larvae don't lay eggs. The larva later crawls out of the plant and into the ground where it builds a cocoon and emerges the following year as an adult moth.

VERY well put Pete Walrath! I

VERY well put Pete Walrath! I am having a bugger of a time and my whole crop is being taken down from 3 directions at once. Flea Beetles, Vine Borer, and Armyworms/cornworms. They took my greens, took my squash, and are working on my tomatoes and peas now. About the only thing unaffected is my strawberry crop which was extra small because of a large Spring seedling crop of tomatoes.

Thank you for your feedback!

Thank you for your feedback! We have updated the copy.


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