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Squash vine borers are one of the most common and destructive pests, killing countless summer and winter squash plants each year. Here’s how to identify squash vine borers, plus how to prevent them or stop them from killing your squash plants using organic methods.
Updated: May 29, 2019
Question: How Do I Stop Squash Vine Borers?
We get a lot of gardening questions via email and our social media accounts. Once we start getting the same question over and over, we know we should write a blog article about it to help out other gardeners who might have the same questions/problems.
Thus, this article… How to prevent or stop squash vine borers using organic methods, which came about due to getting the same question numerous times.
If you’re experiencing a problem with squash vine borers, we hope the info below is helpful!
Context: What Are Squash Vine Borers?
If you’re a new gardener or are lucky enough to live in an area of the world where you don’t have squash vine borers (like the west coast USA), you might not have any idea what a squash vine borer is.
Squash vine borers (Melittia satyriniformis) are the larvae of an attractive orange and black sesiid moth that is active during the day. Due to their similar appearance, many people mistakingly assume that adult squash vine borer moths are in the wasp family. They’re not – they’re moths.
Like squash plants themselves, squash vine borers are also native to the Americas. Adult squash vine borer moths are pollinators. However, they have the unfortunate habit of laying their tiny copper-colored eggs on squash plants.
After 9-11 days, squash vine borer eggs hatch, at which point the larvae chew their way inside the squash plant’s stem and slowly eat the plant to death. A single adult female squash vine borer moth can lay up to 150 eggs in a season!
Adult squash vine borer moth. Image courtesy of Wikicommons. Credit: Pollinator, CC BY-SA 3.0, Link
How can you tell if your squash plant has been killed by squash vine borers?
Here’s how you know you’ve got a squash vine borer: one day you have a healthy squash plant. 24-48 hours later, you walk outside to find a squash plant that is limp and collapsed.
You check the ground and the soil is plenty moist. You give the plant a gentle tug at its base to see if something may have eaten its roots (such as a vole), but it’s still firmly in the ground. Then you notice small holes in the leaf stems and/or the main stem of the plant with brown frass around the opening, indicating that something has chewed its way inside.
You’ve got squash vine borers!
Usually, once the squash plant has gone limp from damage, there is no way to bring it back. This experience can be heart-breaking, especially if you’re relying on a small number of squash plants for a yield.
The above image shows squash vine borer eggs on a squash leaf. These look very similar to squash bug eggs (another squash pest), but they’re spaced much further apart, rather than in a cluster. Squash vine borers sometimes also lay individual eggs on a squash leaf or stem, rather than multiple eggs. Bottom line: if you see a shiny, copper-colored egg on your squash plant, it’s either a squash borer or a squash bug, and the eggs should be removed.
6 Methods to Prevent or Stop Squash Vine Borers
Here are six things you can do to prevent or stop squash vine borers from damaging your squash plants:
1. Apply Bt (Beneficial Bacteria Spray).
Apply an OMRI certified Bacillus thuringiensis (aka “Bt”) spray on the leaf stems and main stem of the plant (not the flowers). Here is a great Bt product you can buy.
Bt is a naturally occurring bacterium found in soils around the world. Research indicates that it is virtually harmless to non-target species (hence its approval for use in organic farming).
If you spray Bt on the stems and leaves of your squash plants once per week (or more if there’s a lot of rain), the squash vine borer’s eggs or larvae will be killed quickly, long before developing into large enough larvae to harm your squash plants. Many organic farmers use Bt spray, and it may be the most effective way to deal with borers and other squash pests.
You can even inject Bt into a squash plant’s stems if the larvae have already bored into the plant but the plant is not yet limp.
To further minimize any potential harm to pollinators (just in case the current science proves to be wrong), spray the plants as late in the evening as possible when daytime pollinators begin to go inactive, and avoid directly spraying the flowers.
2. Mulch the squash plant’s stems.
Keep the main stem of the plant covered with mulch as it crawls along the ground. This method helps prevent the adult Squash Vine borer moths from laying eggs on the stems. If the larvae bore into the main stem area of the plant, it doesn’t take them long to kill the plant.
This method also helps vining and crawling squash varieties set new roots along their stems as they grow, so that the plants can continue to support new growth even if they have been infected by a squash vine borer further down the stem.
If you go this route, also be sure to keep a careful eye on the leaves of your squash plants, since borers also lay eggs on the leaf stems or undersides of the leaves. As mentioned above: squash vine borer eggs are small, round, shiny and copper-colored, very similar in appearance to “squash bug” eggs (Anasa tristis).
The difference is that squash bugs lay multiple eggs in very tight clusters whereas borers will often only lay a single egg in one spot — or if laying multiple eggs, the eggs won’t be tightly clustered.
Another dreaded squash pest: squash bug nymphs. Credit: Pollinator at English Wikipedia, CC BY 2.5, Link
If you see either type of egg on your squash plant, remove them by hand immediately and “smush ’em” (scientific terminology for squishing them between your fingers) or drop them into a cup of soapy water.
Also, if you see one leaf on your plant has gone limp and the others have not, this is a good indication that the limp leaf has a borer inside its stem, especially if you spot an entry hole. Cut the leaf and leaf stem off of the plant immediately, as close to the main stem of the plant as possible. Then make sure you bring swift and brutal punishment to the small white squash vine borer larvae munching inside.
3. Grow resistant squash varieties.
Most summer squash varieties are very susceptible to vine borers. However, there are other types of squash you can grow whose tough, thick stems are not nearly as susceptible to squash vine borers.
Squash in the Cucurbita moschata family are especially resistant. These include Butternuts and our personal favorite Tromboncinos, a vigorous Italian heirloom that can be eaten early as a summer squash or allowed to grow huge to be stored as a winter squash.
If you grow Tromboncinos, be sure you have a lot of gardening space and, ideally, a fence or large, sturdy trellis they can climb on.
Photo: The Tyrant checking out some of her Tromboncino Squash growing over the duck village at Tyrant Farms.
4. Perform squash surgery.
Lets say you find an obvious entry hole on the stem of your squash plant with frass around it, but your squash plant still appears to be healthy.
What to do?
Break out the surgical tools and play doctor!
Squash vine borer in the stem of a zucchini plant. Credit Pollinator~commonswiki assumed (based on copyright claims), CC BY 2.5, Link
A box cutter and a pair of tweezers will do the trick.
First, make a straight incision down the stem of the plant (not across the stem which would sever it) where the hole is located. Cut as little as you have to until you spot the culprit, or culprits if there is more than one.
You’re looking for white grubs with a black head. Remove them with tweezers and dispose of them (our ducks consider squash vine borer larvae and tomato hornworms to be summer delicacies).Then cover the affected area with mulch.
5. Use yellow bowls.
As you may have noticed, squash blossoms are yellow. As such, squash vine borer moths are highly attracted to the color yellow.
Many gardeners/farmers have luck trapping and drowning squash vine borers by placing a yellow bowl full of water in the garden. The color attracts the moths to the bowl. They then get trapped in the water and soon drown.
This method isn’t 100% effective but its a good way to control the moth’s populations and determine when and if the moths are out. In our area, we have two big waves of squash vine borer moths: one in late spring/early summer and another wave in August.
6. Use row cover.
Want to be 100% sure no squash vine borers get to your squash plants (unless they happened to overwinter in the soil where you’re planting)? Use row cover.
Row cover is a lightweight fabric that lets sun, water, and air in, but keeps insects out. The brand we recommend is Agribon and you can get it here for the price of a few grocery store squash.
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Floating row cover. Credit; Aaron Bauger CC BY – 2.0
The downside of row cover? It also keeps pollinators out.
This means you’ll need to play the role of a bee. Go outside with a q-tip (or tiny paint brush) in the morning to pollinate your squash plants by hand.
Using your q-tip, collect pollen from your male flowers (the ones that don’t appear to have tiny fruit at the base of the flower) and rub the pollen on the stigma of the female flowers (the ones that have miniature versions of the fruit at the base of the flower). Then cover your plants back up.
Pumpkins are a type of winter squash. Here you can see male and female pumpkin flowers side by side. Notice the miniature pumpkin fruit at the base of the female flower?
Methods to AVOID when trying to prevent or stop squash vine borers…
A couple of commonly prescribed methods for dealing with squash vine borers that we do NOT recommend:
1. Wrapping the stems of your squash plants in aluminum foil.
Maybe if you’re only growing a small number of squash plants, this method is worth a try.
However, we grow lots of squash plants and our plants have so many leaves and stems, that effectively wrapping each plant would take a week and make our yard look like a metal welder was using it as an abstract art exhibit. Even then, there would still be sections of the plants exposed to borers.
2. Spraying your plants with harmful synthetic pesticides.
This makes as much sense to us as smoking cigarettes while jogging. If you feel you have to resort to using pesticides that are well-documented to cause harm to a wide range of insect, bird, and amphibian species while also being harmful to humans and pets, then please grow something else or purchase squash from local, organic farmers. It’s just not worth it.
Now go get your squash on!
We hope the information in this article helps you have a wonderful squash growing season! If you have questions, please ask away in the comments section below.
Happy gardening!
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I live in eastern California where almost everyone give up on squash due to the hundreds of squash bugs that invade every patch. This will be my last year, it’s simply too much time every single morning to search every leaf and the ground to squish those miserable stinky bugs. I noticed this article mentioned that we do not have the borers out west, but this morning I destroyed some very similar looking eggs on a leaf and was wondering at the time what they were.
Sue: Don’t give up yet! Squash bugs (in the shield bug family) can be pretty easily deterred with neem oil spray. Their eggs look very similar to vine borer eggs – tiny, round and copper-colored. The difference is vine borers will often only lay one egg on a spot or if they lay multiple eggs, the eggs won’t be clustered as closely together as squash bug eggs are.
Sue: Sorry to hear that you’re having so much trouble with squash bugs! Those are different than squash vine borers. It sounds like you might want to try using floating row cover and hand-pollinating your female squash flowers so you get pollination.
I had the borers last year. I read somewhere about planting a few white icicle radishes among your squash and just leave them to grow, that this would deter the moths and their larvae … so far havent had a problem this year in N Alabama.
Toni: Thanks for the reminder! That’s a great tip, especially for smaller bush squash varieties. The only problem is that many of our squash varieties that are susceptible to borers run/crawl along the ground, so it’s difficult if not impossible to grow radishes along the full length of the plants.
[…] Examples of pest insects that fall into this category: ticks (although our ducks eat them all now), Squash Vine Borers, and Japanese […]
What kind of mulch? Wood chips, grass….
Our personal favorite is wood chips, since they break down slowly and don’t blow away. But grass, straw, pinestraw, etc work fine too.
This is my second year growing squash. Last year my plant grew big but it didn’t yield any squash. My plant was riddled with vine borers. It was so bad I had to get rid of it. This year it seems like something is taking the nutrients. The leaves are turning yellow. I noticed 3 bugs on the top of the leaf where the stem meets. They almost resembled a spider…they were brown and had 6 legs. Does anyone know what these are and how to deter them?
It sounds like you’re describing squash bugs and/or squash bug nymphs. These are quite common. They’re sap-sucking insects that can really take a lot of energy out of your squash plants if they proliferate. We usually just: a) remove them by hand and drop them in a bowl of soapy water, and b) keep an eye out for their eggs on the top and bottoms of the leaves (the eggs look like clusters of tiny copper beads) – remove the eggs immediately by hand too.
You’ll usually see bunches of the nymphs on the undersides of the leaves after they’ve hatched. The adults tend to stay closer to the ground on the undersides of the stems – if you gently lift up your plants, you’ll likely see pairs of the adults on the bottom side of the main stem, if you have an infestation. Once you get rid of the adults, no more eggs or nymphs. If you’re not comfortable with insects, you can also use an OMRI listed/organic insecticide like spinosad (http://amzn.to/2rACq3n). Another option is to start the season out using a small row cover so that squash vine borers and squash bugs can’t get to your plants to start with – the only challenge there is making sure you remember to pollinate the flowers by hand since pollinators can’t get to the plants either.
One other thing to note is that squash form male and female flowers. To get fruit set, you’ll need to have a male flower blooming at the same time as your female flower(s) are blooming. That’s usually not a problem if you have multiple plants, but it could be a challenge for you if you only have one squash plant growing.
Hope that helps and please let me know if you have any other questions!
Hi, Aaron. This article was greatly helpful. Thank you for putting it together. I even put “yellow bowls” on my mental shopping list until I went on to read that we don’t have Squash Vine Borers here in Oregon.
I do have one question. You mentioned in the introduction that many gardeners mistake the adult SVB as some type of wasp, but then, in the Number 2 “Mulch the Stems”, you actually referred to it as a wasp. Was that a slip of the pen? Or am I failing to understand your meaning?
Great catch, thanks Jo! I’ve probably read this article 5 times and didn’t catch that error. It’s now corrected, so thanks again!
I lost so many zucchini and cucumber plants last year it wasn’t funny. I got so mad I got my son’s propane torch out and burned the eggs on the leaf and then found the squash bug and burned her too. A few leap hoppers got in the way so they went too, lol… This year I got some serious stuff to spray the garden with an over 50 million nematodes. I had a beautiful honeydew seedlings and they were all dying one by one. Those were the fungus gnats I think because they were too small, but we did find little white worms in them with black heads. We tilled the soil and got rid of any rotting plants from last year (I don’t do that, my neighbor does) and starting fresh, and we are getting a truck load of new topsoil too. So I hope this Pyganic and the nematodes will help but I will also be putting tin foil on the stems. I also read where you can put rhubarb leaves wrapped around the base of your zucchini. This worked for the seedlings. I am trying everything I can to get some zucchini, cucumbers and honeydew this year, even the propane torch, lol….
Yikes! Sounds like you’ve got a lot of work cut out for you. Something that could cut down on your time investment is to use light weight summer row cover which completely blocks out insects: https://amzn.to/2EJJD2X (that’s an affiliate link where you can buy the product we recommend on Amazon if you want to). If you go with row cover, the only things you’ll need to worry about are:
1) making sure enough water gets through to keep the plants irrigated (drip lines could solve that problem); and
2) since pollinators will also be blocked out, you’ll need to go out in the morning and hand-pollinate the plants with a paintbrush or q-tip, otherwise you won’t get fruit set.
That seems like a lot of work too, I don’t have the patience to go out there every morning with a Qtip. I am going with a different approach. My son just got done tilling the whole garden. We are going to add another 2-3 inches of top soil and my neighbor bought the nematodes and I bought the Pyganic, plus I have the yellow sticky pads. Removed all the wood and all the rocks so there is nothing for them to hide under and I added my lime. We have to get more soil, because about 4 inches down its nothing but coal ash from years ago. We also put up a new gate all around, that won’t stop bugs but it will stop critters. I’m not messing around this year, I am determined to get a great garden, all I pray for now is a good summer, not too much rain and not so hot. My garden is 30 feet in length and 12 feet width, so you see it’s not a little garden. Wish me luck…
Luck!
Well I read this article again and I am going to try the bt spray this year. I will still do my foil and use my torch, lol, but if I’m not out in the garden at noon, the squash borers always get at my plants.
See I am retired and spend most of my days out in my garden, its relaxing except for seeing the squash bugs or the borers.
Last year I killed many eggs and bugs, maybe if they are intelligent they won’t come back, lol…
My zucchini plants look healthy but all the squash get soft at about 2-3 inches long and turn from dark green to light green to yellow and then brown. They rot. I wasn’t sure if this was due to incomplete pollination, too much or too little water, or squash vine borer. I placed tinfoil on all the stems early in the season and haven’t seen any fras at the base. Any ideas what’s going on? Thanks.
Fawn, sounds like your female flowers aren’t getting pollinated. When that happens, the fruit fails to mature after the flower falls off and soon shrivels and rots. If you don’t have pollinators (native bees, wasps, honeybees, etc), then you may need to hand-pollinate the zucchini yourself using something like a q-tip or a paint brush. Take pollen from a male flower (the ones that don’t have tiny zucchinis at the base of them) and rub it on the stigma of your open female squash flowers (the flowers with a small zucchini at the base). Once pollinated, you should get mature zucchini.
Hope that helps!
Does planting Marigolds help with the moths themselves coming around?
Hi Chip! We have not found that to be the case nor are we aware of any research indicating as such.
I have my zucchini in self watering containers. They survived until the 3rd week of July before getting killed by the borers. some survived, but it ain’t pretty. The containers are 20 gallon and full of roots , so I thought the plants were turning yellow due to the roots needing more room, but it was the bugs. Bigger containers next year and maybe row covers. I am willing to spoil my zucchini
Good luck next year, Todd! As we mention in method #1 in the article, a great lazy-man’s solution is Bt spray, which kills the eggs/larvae before they can damage your plants. Here’s the product we recommend for that: amzn.to/2jwDD3n
lots of great information vine borers are horrid here but last year watched REALLY closely and got about 100 squash so it was great… lot of work looking for the eggs and catching the bugs by hand though in oklahoma
Thanks for your feedback. Glad to hear you had success getting squash and catching your squash vine borers before they became a problem!
Can the Bt spray also be used on cucumbers, pumpkins and tomato plants? Have had trouble in the past with those as well. Last summer was rather rough!
Debbie: Bt can be used as a foliar spray on any plant. Caveat: keep in mind that Bt is not a contact poison, it’s a bacterial toxin that shuts down larvae’s digestive system after it’s ingested. There are also different strains of Bt insecticide because each insect is a little different and not all strains of Bt work on every type of insect. Here’s a more detailed summary of how Bt works if you’re interested: http://www.bt.ucsd.edu/how_bt_work.html
Long story short: make sure you know what type of insect you’re trying to target, so you can be sure to match the appropriate Bt product/strain to that target insect. The bottle will say what insects it’s designed to target. For instance, the Bt product we recommend in this article (Amazon affiliate link) is the strain: Bacillus thuringiensis var Kurstaki. That strain of Bt is also effective on tomato hornworms.
That make sense? Please let me know if you have any other questions.
If I pick the eggs off the plant, do I need to do something to kill them or just removing them from the plant will be good enough?
You should either drop the squash vine borer eggs into a container of soapy water or smush them to kill them.
What about a sticky spray like tanglefoot at the base of the stems for the borers?
Great question! Based on our experience with squash vine borers, we don’t think tanglefoot would be effective. We’ve seen borers lay eggs on the squash leaves, stem-leaf joints, all along the stems, and the base of the plant. From there, we’ve seen the eggs hatch and the larvae bore into the stem starting at the very top of a leaf stem before working their way down to the base of the plant, where they’ll eventually kill it. So, tanglefoot wouldn’t be able to prevent squash vine borers under those circumstances.
I have went two fold this year. I planted Geraniums all around my garden and I inject Captain Jacks Dead Bug directly into the root of my squash about 1 inch above the soil line. I have done it for 2 months now and have had very good success. I inject them every Monday morning.
I planted seeds and have 2 plants that had multiple (3) roots come up and I lost 2 of 3 yesterday on both. I wasn’t as diligent as I should have been and was only injecting one of them (I thought it was just one root with different stalks..yeah I was dumb I know). I was kicking myself yesterday for being careless. However, every other plant (10) has done great. No issues.
I was researching squash varieties that are parthenocarpic and came across your article. I may have missed it but you didn’t address growing varieties that are parthenocarpic under row cover (agfabric) as an alternative to varieties that would require either removal of the fabric for pollination or hand pollinating. Thanks
Great point, thanks Tawana! We tend to write for and cater to gardeners and market farmers who use open-pollinated and/or heirloom seed varieties. We’ve got nothing against hybrid seeds or hybrid squash varieties bred to be parthenocarpic though. If organic growers want to grow parthenocarpic squash under row cover, that’s certainly a viable option to control squash vine borers.
I had squash vine borers here in PA every year. This year I bought BT and also Neem for the cabbage butterflies on my brassicae. OK. So. I thought you’re supposed to inject the stems with BT but really, I got syringes and tried this, but it really wasn’t working, very hard to inject the stems, plunger doesn’t want to go down. Now, that said, I don’t think my plants were “entered” yet. I saw one moth and killed the little witch with my bare hands. I then preventatively attempted to inject the BT mixture to no avail, so in desperation, I heavily doused ALL the stems of the plant, including main stems and leaf stems, with BT. I then busted out my neem oil spray mixture which has worked HEAVENLY for my brassicae this year. Last year the cabbage butterfly caterpillars murdered all the various brassica in my garden, this year, I get a handful of tiny pinprick holes and the baby caterpillars die and NO damage is done! Love it! So I sprayed the neem mix on the squash and zucchini stems too. Hoping if the borer moth laid eggs and the baby caterpillars try to eat the stem they will die… by reading your article, that seems possible… I didn’t know if this would work I thought only injecting worked. I also didn’t know which would work better, neem or BT. Do you think the neem or BT will REALLY kill the borers if they try to enter the plant? So far, I’ve never seen squash bugs. Just borers. Last year I ripped out all my squash and zukes because I found some borers and didn’t want them overwintering and hatching the next year. I have NEVER had borers bother my cucumbers, though. Sorry for the LONG post but I’ve been searching for years for a fix…
No problem on the long comment, Eva! Squash vine borers tend to get people riled up because they’re such a terrible pest.
Our thoughts:
-Bt works when the larvae EAT it. Without getting too graphic, it’s a bacteria that basically causes target insects’ digestive system to explode. It’s not a contact pesticide. It’s organic/OMRI listed because it’s a biologically-based and because it doesn’t hurt people or other non-target species.
-There’s no need to squirt Bt into the stems of your squash plants unless the squash vine borer larvae have already eaten into and gone inside of the stem. Simply apply Bt preventively as a foliar/stem spray. As soon as the squash vine borer eggs hatch (if not before) they’ll ingest small amounts of the Bt and die before they can cause much or any damage to your squash plants. If you have really heavy rains, re-application of Bt would be advisable.
-Neem oil is also an organic/OMRI approved pesticide derived from neem trees. There are lots of different biological compounds in neem oil and the way it deters and/or kills insects is not fully understood given all the different compounds and mechanisms involved. Neem does disrupt the hormones needed to allow an insect to go to the next stage of its life cycle (similar to the way Bt works). We’ve noticed it also works as a contact pesticide, probably by coating an insect’s skin and suffocating it. Neem is also a deterrent because insects don’t like the way it smells.
-Both neem and Bt can be used together to help you with your squash vine borers, but you probably don’t HAVE to use both – although using both will likely reduce the likelihood of losing your plants to squash vine borers to around 0%. If we had to choose between only using one or the other, we’d probably choose Bt.
Thank you so much, yes those borers do rile me up because I have been able to find solutions for everything else so far, but borers have been tricky because they get inside. I tried row cover last year but that didn’t work, they got muddy, and ants began to farm aphids on the plants. The row cover actually seemed to stunt the plants growth – not a fan. The neem has really prevented aphid farming on my plants. The BT has worked beautifully to keep caterpillars off my brassica. Anyway thank you I now feel much more confident that I can grow my zucchini and squash and don’t have to worry about borer moths. We only managed to kill one, the rest were too fast for us (: and since we have lots of regular wasps (the good guys of our garden) if we swatted too much at the borer moths we would’ve been stung by a wasp.
Hi! My garden of zucchinis, spaghetti squash, and pumpkins have been hit hard by this. Some sections of the plant are dying but some are still green. I have been using a small kitchen knife to slice open the plant stems at indicated points (frass, eggs, wilting, seeing a shadow inside the plant when the sun hits it, etc) and murdering the numerous jerks I’m finding within. The zucchinis have had the most invasive and extensive surgery at this point. If parts of the plant are alive and thriving can I expect any of them to make it and continue to fruit? Also, I grew all these plants in buckets with potting soil, should the soil be disposed of if I don’t find any larva in it?
Hi Kristen! Sorry for the delayed response. Answers to your questions below:
Question: If parts of the plant are alive and thriving can I expect any of them to make it and continue to fruit?
Answer: It depends. Some will, some won’t, depending on the extent of the damage and how much nutrition the sections are able to get via new roots they set.
Question: Also, I grew all these plants in buckets with potting soil, should the soil be disposed of if I don’t find any larva in it?
Answer: The late instar larvae of squash vine borers burrow into the soil before pupating. A few might do this inside your pot/containers, but more likely any that make it to that stage will burrow into the soil outside of your pot to overwinter especially giving the sprawling and crawling nature of winter squash. You generally do NOT want to plant the same plants in the same soil year after year in order to prevent the buildup of certain pests and diseases that like those particular plants (e.g. crop rotation). So, yes, if you intend to grow squash in the same buckets next year, you’ll be better off starting with new soil – or you can just plant a different plant in the buckets next year (ex bush beans, eggplants, etc.).
Hope this helps!
Had a pumpkin patch with vine borers what crop would you recommend this year
How can I eradacate them from soil or do they die out and what pumpkin is hard stem to detour borers
Thank you
When mature squash vine borer larvae emerge from your squash plants late in the growing season, they go into the soil to overwinter as pupae in cocoons. Then they become the first round of moths that lay vine borer eggs on your plants the next season. (There can be multiple generations each year depending on where you live – we usually have at least two generations here where we live in South Carolina.)
There’s not any way to eradicate the squash vine borer pupae from your soil without applying biocides to your soil, which we’d highly recommend NOT doing. Using cover crops during the cool months could potentially bring in enough ecological controls (e.g. soil-borne predators) to eat the larvae, so that could be worth a shot. Worst case, you end up with healthier more microbially active soil!
Probably the two easiest organic methods of control for squash vine borers, as mentioned in the article, are:
1. Growing squash in Cucurbita moschata family that are resistant to borers due to their stem structure. Examples: Butternuts and Tromboncinos.
2. Staying on top of the new eggs, especially the first generation of the season, so you break the life cycle. Hand removal is more difficult especially if you have lots of plants, but there are good organic products like Bt that you can apply as a foliar/stem spray that kills the eggs and the larvae with minimal off-target effects. Here’s an Amazon affiliate link where you can buy a good Bt product: http://amzn.to/2jwDD3n.
Let me know if that answers your questions?
for the yellow bowl method, do i use just plain water or do i add liquid soap?
Either works, but certainly can’t hurt to add a little soap so long as you don’t have a cat or dog that’s going to gulp it down. If you do use soap, we’d recommend you get unscented soap so it doesn’t deter the adult squash borers from visiting.
We have been plagued with both squash bugs and squash borers for many years. This past summer we were away from home (Ohio) during the entire month of May (when we normally do all of our planting). We didn’t get our garden in until the second week of June. And what do you know – no squash bugs and no squash borers! It was wonderful. I would suspect this had something to do with the timing of the emergence of the larvae. Your thoughts?
Very interesting, thanks for sharing Carol! Yes, you likely missed the first generation of squash vine borers and squash bugs. We get a few different waves down here in the south. Sounds like you should try to stick to the same growing calendar as you did last year and see if you get similar results. Please keep us posted regardless of what happens so other people can find out too!
I live in Columbia, SC… moved here from the west coast where these aren’t a problem. Planted pumpkins this year, just started coming up (I know it’s kinda late in the season, but bth they started growing in some compost I started last year and I figured “why not”). I’m worried the vine borers are going to get them. They got my zucchinis last year (which were in a pot, so different soil). I was hoping that it may be late enough in the season where they are done laying eggs, but based on the comments that Aaron is leaving it sounds like they have multiple “rounds” of egg laying in SC. Am I not safe? Will the adults be back in the fall?
I have armed myself with BT, nematodes, and a large yellow bowl. If I dose the vines with BT weekly, along with those other countermeasures, should I also get floating row covers to try to put over my vines, or is that just excessive at that point?
You should be fine on squash vine borers with those methods of prevention, but if you have other squash pests like squash bugs, the row cover will take care of those.
You’re not too late on your pumpkins, especially given how long warm weather has been lasting the past few years. Unfortunately, you won’t miss squash vine borers in SC, no matter when you plant your pumpkins. Yes, they seem to have 2-3 waves here. Good news is that there are some pumpkin / winter squash species that have thicker stems and will grow right through any borer damage they do get since they set new roots at each joint. (See article for species.)
Last year I had to resort to vine surgery to save my crop. This year I purchased a Squash Vine Borer Trap.
The attractant lure entices the adult males to a sticky destruction. My winter squash plants, so far, look
healthy.
Good to know! Please keep us posted on how things go as the season progresses. Mind sharing the type of squash vine borer trap you’re using?
Will yellow jacket traps by Rescue attract the orange and black sesiid moth?
Hi Doug. Sorry, but we don’t know the answer to that one. You could try contacting the manufacturer to see if they have an answer from any field trials they may have conducted.
Aaron, I purchased the Squash Vine Borer Trap online from Burpee. The pack consisted of two traps and two lures. It has been about a week since I posted my original comment and I am very pleased to still see no evidence of borer activity.
Great to hear! Fingers crossed for your continued success against squash vine borers.
Hi Aaron, Just found your site. Your advice is very clear, concise and helpful. I’m heading out to the garden in a bit with BT as I spotted mama squash vine borer yesterday. I do have a question about all those excessive fading leaves on my zucchini/yellow squash plants. I’m growing them vertically this year in the hope of being able to spot trouble easier. I am training them up tomato cages and it’s much easier to keep an eye on the ground area where the main stem is. However, spraying to coat all the leaf areas will be next to impossible due to the dying/broken leaves. Is it ok for me to trim these off? Many thanks.
Hi Marianne! Yes, by the time they’re yellow-brown, the amount of energy they contribute to the plant via photosynthesis is virtually non-existent. Feel free to remove them.
Hi there, what a great set of comments you’ve got here! I have a pumpkin plant whose stem near the base has become almost detached, and looks similar to photos of the damage you’ve described. I assumed it was some kind of rot from excessive rain a few days in a row. But The other plant next to it looks fine at the base. What I see is dozens of tiny bugs that look like red termites or super tiny red ants, and they’re carrying tiny specks of white as they run away from the plant. What could these be? They don’t sound like the larva you’re describing, but they do share the color of the eggs. Thanks for any insight!
Hi Sarah! It sounds like you’ve got two things going on: 1) vine borers have eaten the stem of your plant, and 2) another insect species is moving its eggs or larvae from the area to a new location for some reason. It’s hard to say for certain on either issue without seeing photos though. Are the red insects coming from inside the stem of the plant? Are they moving the white specks to somewhere else away from the plant?
I have found borers in one cucumber fruit, not the plant itself, how do I protect the other fruit?
Ann Johnston
Columbus ga
Hello Ann! The worm in your cucumber fruit is not a squash vine borer. It’s very likely the larvae of a pickleworm moth (Diaphania nitidalis). The best organic solution to protect your cucumber fruit is going to be Bt, which you can but here: https://amzn.to/39yEwDQ
I live in Blythewood, SC and reluctantly used Sevin spray on the part where I saw the damage from the larvae. It seemed to work. I’m all about organic but sometimes you need chemicals. The amount of energy and water and dirt and time I put into these plants would be such a waste to let them die. I work full time
And don’t have time
To inspect my plants twice a day and do surgery on them. My garden is to feed myself and my neighbors. I did not spray it near the flowers as I do not want to hurt the bees. I have a yard full of moles and frogs wish they would take care of these pests. Next year I will plant only resistant varieties. #growfoodnotlawns
Hi Ashley! A simple organic solution for you to use next year is Bt, as mentioned in the article. Just spray it on every 7-10 days and you’ll control your squash vine borers. Bt is a type of bacteria, not a poison, and won’t harm other critters in your garden.
Hi Aaron, I just cut open an acorn squash and found what I believe is a svb worm in the fruit itself. It wasn’t deep, just inside the skin. The hole and brown frass look similar to what I’ve seen on my infected zucchini plants in the past. Have you ever heard of the worm in the fruit?
Hi Kevin! It’s hard to say for certain without seeing a picture, but it could be a squash vine borer. It could also be a pickleworm (Diaphania nitidalis), which bore into squash fruit as well. You can use the Bt product recommended in this article to control both pickleworms and squash vine borers.
The next step is to check the for holes near the base of the plant. Small holes surrounded by a sawdust-like material (the squash vine borer’s frass, or droppings) is all that is needed to identify the presence of this pest. The squash vine borer eats the inside of the stem of plants, which will cause plants to rot at the site of the entry.
Terrific article