Squash Vine Borer

How to Prevent and Get Rid of Squash Vine Borers

Squash Vine Borer larvae
Wikimedia Commons

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. This may be the result of a squash vine borer (SVB), which is a type of moth that lays its eggs at the base of squash plants. When the eggs hatch, the larvae burrow (or “bore”) into the lower stems, weakening or killing the plant outright.

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

The borers overwinter in soil as pupae in cocoons. When the adult 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 usually only 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 around the bases of squash 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 squash vine borer is a moth about ½ inch long. It has a gray or black body, marked with orange-red on its abdomen, legs, and head. The hind wings are transparent and the front wings are metallic green.

Squash vine borer moth. Photo credit: Judy Gallagher/Wikimedia Commons
Photo credit: Judy Gallagher/Wikimedia Commons

Identifying Squash Vine Borer Damage

  • First, the leaves of the plant will likely start to wilt inexplicably.
  • Look for holes at the base of the plant and green or orange-yellow sawdust-like “frass,” which is the chewed up stem that the larvae produces as it burrows into the plant.
  • Squash vine borer larvae 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 Prevent Squash Vine Borers

As with most pests, prevention is key. 

  • Sometimes, the best solution is to start your squash as early as possible. This way, plants will be strong enough to withstand any mid-summer attacks and you may even be harvesting before squash vine borers become active. If you plant early, you may need to be prepared to cover your plants in case of late frost.
  • Do not plant squash in the same area two years in a row. Squash vine borers overwinter in cocoons in the soil. Also, clean up and dispose of ALL plant debris in the fall.
  • As soon as the squash plants are finished for the season, dispose of them. Till the soil in the fall and spring to get rid of overwintering pupae.
  • Physical barriers can be an effective means of keeping squash vine borers at bay:
    • Cover the plants’ stems with a barrier, such as strips of nylon stockings or aluminum foil, to prevent egg laying. 
    • Before flowers appear on the plants, use row covers to keep squash vine borers away. The covers will need to be removed for pollinators, eventually. This will not only give you a head start over pests, but protect your plants from strong heat and frost.
  • Adding parasitic wasps to your garden prior to the vine borer’s egg stage can be helpful, as these wasps are the borers’ natural enemy.
  • If you give up on zucchini, which is susceptable to vine borers, try growing a squash that’s more resistant. Butternut squash and Cucuzzi (Lagenaria siceraria)—also known as the snake gourd—tend to be resistant to squash vine borer attacks.
  • Plant extra squash for the pests! This pest is around for only 6 to 8 weeks and can only eat so much (or so we think!), so making sure you have plenty of plants to spare can help you avoid a total loss for the season.

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.

How to Get Rid of Squash Vine Borers

If you’re already seeing signs of squash vine borers, use these methods to get rid of them or at least minimize their damage to your crops.

  • If you catch them VERY early, you can manually remove the squash vine borer. Locate the entry point of the larvae, then slit the stem lengthwise with a fine, sharp knife to remove the larva by hand. One plant can house several larvae. Carefully remove the larvae without doing more damage to the plant. 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.
  • If you can find the entrance holes and “sawdust,” try inserting a wire and thread it through the stem for some distance to kill the larvae inside.
  • Sprinkle diatomaceous earth around the stalks when the squash vines are small or the threat of squash vine borers is high (early to mid-summer). 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 leaves of the plants.
  • There are insecticides that work, too, but timing is critical; they are only truly effective when applied at the time when 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.
    • Insecticides containing the ingredients carbaryl (Sevin) or permethrin will work on squash vine borers, too. Always be sure to read labels and warnings carefully before application of any insecticide.
    • 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.
  • An old folk remedy from The 1963 Old Farmer’s Almanac says that wood ashes were effective against the squash vine borer.

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

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Reader Comments

Leave a Comment

No on the garlic

My garlic was right by my zucchini and cucumbers, onions too. I will try nasturtiums.

Worse year ever for these disgusting things

I have been gardening for over 30 years and never ever had a bad zucchini crop. Well, I finally met the squash borer and boy did they go to town on my squash. First limiting the plants growth but I got one zucchini until I decided to look inside the stalk. I found one that was over an inch long and he feasted on inches of the stalk. Well I got so mad I pulled up all my plants and dug up the soil and found babies, look like little white worms and burned them with a blow torch. Also found tons of ants protecting their eggs and of course aphid eggs on the roots of my zucchini. The Northeast is getting a lot of heavy rain and I do believe this is the culprit also my friend leaving rotting and old plants in the garden from last year wasn't a good idea (no more of that). I also lost my cucumbers, honeydew melon and cantaloupe, so they do go after cucumbers. I have read a few articles and found the foil around the stem, but also using a rhubarb leave as a cover for the seedling (yes I am starting over) and will try this method too. We also got nematodes hoping they will kill the little ones as how can they get to the big ones in the stalk? We have Sevin too and will treat the soil with this as the little ones are the ones I am worried about now with the new seedlings I have. I like the picture of the moth, I thought it was just a regular white moth but now I know what to look for. The other comment from that man just didn't see the picture? Also there is a rhubarb tea that is poisonous that I will try in the soil. I will try anything now before the season is over, but next year I plan on turning the soil over, getting millions of nematodes not before I burn some wood right in the garden to add some wood ash to it and hopefully burn the little babies before they go hide for the winter. I will not let these little bas***ds ruin my garden. My advice is don't give up, get determined as home grown veggies vs. grocery store is well worth all the work and frustration. Don't let any pest ruin your fruit and veggies. Get a blow torch and burn them all, lol...

borer

Interesting Gloria, I live in the North East, Pennsylvania and lost my Zucchini and Gourd plants. What a disappointment. It happened so fast.

squash borers

We have lost several plants in years past to the dang borers!! Not anymore:) My husband is vigilant with his little shaker can of Sevin dust.
If it gets watered or washed away by rain, here he goes and sprinkles more. He keeps a little fine dusting around the stems (and up on the stems) of all our plants. NO borers. I am not usually so agreeable to using chemicals (in this case carbaryl 5%). But, we have tried everything else. This really works.

Hopeless

I did the manual "surgery" to remove the borers one year, and it was probably the most disgusting job I've ever had to do for my garden. Those worms wreaked havoc on my garden and even after painstakingly removing them they still kept coming back. I don't have the room to plant trap crops, nor do I feel they work as they just encourage more breeding of the bad insect.

This year I'm seeing the moths but I have no practical way of preventing them from laying eggs. Going to do what I did last time and use a systemic pesticide that both kills the borers and degrades into harmless compounds before harvest.

Try the Yellow Sticky Traps

I just found these on the web after hearing about them. The moth will fly onto the sticky side and get trapped. Also good for aphids and whiteflies. I just ordered some tonight and hopefully they will work. It said it attracts moths so I'm willing to give them a try. You can't give up.

squash vine borers

This is the second year I have had to deal with these monsters. This year I have been diligent picking the eggs off all my plants, (very time consuming) but yesterday I found 2 plants with evidence of the borers and had to pull the borers out - so I obviously missed at least 2, but probably more eggs. From my observations the moth lays the eggs on the top areas of the plant, I have found eggs on the tops and bottom of leaves, on the curly strings that catch the trellis netting, the leaf stems, bases of the flowers, and the plant stems, all mostly on the upper parts of the plants. Its extremely frustrating and heartbreaking to see the plants die after so much effort to protect them. In my search for a solution I did come across some netting for moths/butterflies - similar to deer netting in price and material, but it is NOT sold in the USA, at least not in a cost effective way. The UK and Europe sells the 'butterfly netting' for a similar price as deer netting $70/roll 7'x100'. Some companies here make something similar, but the price is triple or more; and to have it shipped from outside the US raises the price too high. This is the second time I have found solutions outside of this country that are available to other country's consumers - I can only think it has something to do with the chemical companies not wanting us to have organic options....very frustrated!!

Squash Vine Borers

The Editors's picture

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

The Editors's picture

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

The Editors's picture

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.

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