Squash Vine Borer

How to Identify and Get Rid of Squash Vine Borers

Squash-vine-borer
Squash vine borer, by Massiv99: Wikimedia Commons

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Are your squash plants suddenly struggling? It could be the work of a squash vine borer. 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 (burrowing) into the lower part of the stems.

Found throughout the eastern United States, squash vine borers attack squash, zucchini, pumpkins, and gourds. They prefer Hubbard squash and are not as fond of butternut squash. Other cucurbits, like cucumbers and melons, are not usually affected.

The borers overwinter in soil as pupae in cocoons. When the adult clearwing moths emerge in early to mid-summer, they lay eggs singly or in small groups at the base of plant stems. The eggs will hatch within 1 to 2 weeks of 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 of North America, 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.

Identification

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.

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

Identifying Squash Vine Borer Damage

  • First, 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 start to rot at the site of the feeding first.

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

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. One plant can house several larvae. After removal, cover the slit stem section with moist soil above 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 only truly effective when applied at the time that eggs are hatching.
    • The bacteria Bacillus thuringiensis v. kustaki (Bt) is a natural insecticide that can be injected into and applied to the squash stems, however, it is not usually effective because the larvae are protected inside the plant. 
    • Many find carbaryl (Sevin) to work, too.
    • Consult your local cooperative extension service 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.

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

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 frost.
  • 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. 
  • Adding parasitic wasps to your garden 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 another main squash and zucchini predator: the squash bug.

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

Plants Affected

Reader Comments

Leave a Comment

Squash Vine Borers

Hi Vicki,

It sounds like you’re putting in a lot of effort into protecting your garden, and that’s unfortunate the butterfly netting is too expensive. Try going out with a butterfly catching net, or tennis or badminton racket in the evening. If you see any of the moths near or on your plants, capture and dispatch of them before they can lay the eggs. Each can lay over 150 eggs in its lifecycle, so stopping even one before it lays will do a lot of good. Also, next season try growing a more resistant variety of squash called Cucurbita maxima, which grows supplemental roots from its vines as it grows outward, allowing it to still produce squash even if the main stem were to die.

SVB

I know this is a year old so you may have come to some resolution by now, but I thought I would comment anyhow. I thought your comment was very observant. I live in north Texas and I have dealt with SVB for 4 years now. It is definitely a formidable pest for a home gardener. I grow organically and have tried all of the methods recommended by supposed agricultural specialists and internet advisers such as wrapping the base of the stem, manual removal of the larva by “surgical cutting”, hand picking the eggs, injecting BT into the stem, stringing a wire to impale larva, and row covering. Of all these methods, the only successful method by any means at all was row covering. Every other method fails for their respective reasons. Aside from row covering, planting early may be an option that would allow at lease some harvest before the arrival of the borer. I have done that before with a few zucchini coming off the vine before infestation, but in Texas, you have a much shorter time before temperatures warm up and the SVB arrives. Other than that, I have learned to grow varieties of cucumbers that they leave be. I am unable to grow pumpkins or winter squashes, gourds or anything of the sort. I do think there is some truth to what you say about some places making organic methods less pragmatic. Good luck to you in your garden.

What resistant varieties do you grow

What varieties do you grow that are more resistant?? Thanks! Kate

SVB

I'm in North Texas as well. Just realized all my acorn squash and pumpkins are goners. Sad. Thanks for sharing your experience.

inexpensive netting

I checked out my local craft store and toille is a very fine netting used mostly in wedding and party decorations. It costs only $1.25 a yard.

Netting

I've resumed my search again for a netting option. Last year I bought a bolt of inexpensive Tulle and covered all the squash. It was somewhat successful - the Tulle created other issues such as aphids and lack of air circulation because of the tight weave. The plants that did not get aphids were protected by the Tulle, but it started to disintegrate at the end of the season and rip easily. Its labor intensive to redo the Tulle each year as well as not very environmentally friendly to keep replacing it or economical for that matter. I still cannot find the 1/6" or 1/8" netting here in the states for a cost effective price - shipping doubles the cost from anywhere I have found it available. Does anyone have a connection in the USA for cost effective netting? China can deliver it, and its reasonably priced, but the minimum quantity is way too much for a non farmer!

netting

you can get 50 yards of the tulle wedding net 60 inches wide for about $20. Google for source

Squash vine borer

Instead of using a costly butterfly netting, try using Tulle as used in weddings. I have but you have to self pollinate. It works if they don’t come up from the ground.

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?
Thanks.

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

Wood ash

I don’t know about wood ash and it’s effectiveness for the borers, but here in Georgia a lot of people swear by it as a general way to keep away critters ( snakes, various pests and small animals)

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! :)

The Mayo Technique

I am really excited to try this. It has been too long since I've had a home grown squash!! Is it possible to post a pic of your protected plants? This sounds really interesting!

Mayo Technique

Can you post a photo of this?

Cut hat or straw

I would love to try this.... But the cost of cut hay or straw is definitely giving me pause. And it is a recurring expense because I can't gather it up and reuse it.
If you cut your own, which it sounds like you might, are you getting a bale and cutting it up or do you have a source for cut hay or straw before it is baled? Maybe next year, after I retire, I would have time to cut my own!!

I am trying covers and, as much as I don't like poison, I will try that as well this year.

I agree with many posts. SVB are wicked and I have tried many options to keep them out of my plants but I refuse to give up!

Mayo matrix photo would be great

Any chance of a photo of this matrix of hay?I'm having trouble visualizing exactly how to do this. Thanks.

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
05/17/2016

Worms

I couldn't agree more. My entire crop was decimated last year. This year it will be spray and dust, dust and spray sevin.

research

I realize the original post is over a year but you raise a point I would like to address. The reason we can go to the moon and treat many cancers is because of research dollars. I've seen many an opinion piece by irate individuals because government agencies had the nerve to give a researcher $100K to study the reproductive cycle or life span of some stupid, useless bug. I've done research and it takes a lot of time and a lot of money. Then when you finish that study you need to study if the remedy is harmful to humans, pollinators or species that prey on other pests. Again more time and money. The sad truth is the population does not support scientific research unless it is the big picture and/or they can see an immediate and obvious benefit for humans.

My solution for Vine borers and Squash bugs

I have been gardening since I was 22 and I am now 59, never have I seen this problem like this before. Last year was the worst yet so far. My friend slit the stem and found two huge ones. I on the other hand have no patience and just uprooted and started over again. I did read if you take a rhubarb leaf and wrap it around the base of the plant, well that worked but I also think it worked because I killed most of the ones in my garden already. But I got some zucchini, not much but I did. No cucumbers at all. How did I kill them, eggs too, your going to think I'm nuts but I got a propane torch used for plumbing. I go out there and if I find anything that resembles a stink bug, wasp, even ants I burn the suckers. Eggs that are on the back of a leaf I break it off and burn the eggs. My neighbor and I bought nematodes about 30 million of them and let them loose, we couldn't really tell if it worked, not really with the gnats. The gnats and the vine borers killed my honeydew melon and they were beautifully plants. So, this year, we have many gnat traps, more nematodes, will try again the rhubarb leaves and the foil and I have some netting too when the seedlings are young. I will always use my trusty propane torch to burn beetles, June bugs, ants, leaf hoppers, you name it. The ants actually run from me anymore, lol... I light the torch as soon as I get into the garden early in the morning and I have burned a few while they were sitting on a leaf. They can't lay eggs if they are fried, they can't fly. I then pick them up and put them in the garbage and that's it. Oh, and this year we are tilling the garden. My neighbor likes to leave old dead plants from last year in the garden, but we got rid of them. No more big flat rocks or boards either. Don't know what happened that these bugs are just out of control and where did they come from. We need to have an immigration law against this bugs from hell, our food is at risk.

You made me laugh, its "Just" what I needed dealing with this

Thank You!
Its odd though~Years ago when we grew zucchini we had so much we couldn't give it away. And now~ Most of us are lucky if we even get any. I wonder why???

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.

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