How to Outsmart the Squash Vine Borer

Do You Know the Squash Vine Borer?

Do you grow summer squash? Do your plants go crazy and produce so much squash that you run out of friends and neighbors willing to take any more excess squash off your hands? If so, you do not need to worry your pretty little head over this painful tale. In fact, stop reading now, lest you have horrible nightmares. Dig up your recipe for Zucchini Surprise and go in peace.

For the rest of us, who battle the notorious squash vine borer every spring, we are headed for the battlefields of the Borer Wars once again. We will find out just how much abuse we are willing to take in the name of those delicate, hard won trophies – summer squash. We will discover the nemesis that drives the gentle backyard gardener to become a warring desperado. Do you appreciate a fair fight?  Or, are you just out for revenge?

Squash heartaches: Everyone Enjoys My Squash, Except Me!

A Tale of Gardening in Two Cities

OK, sit back and enjoy this classic tale: One fine spring day, Dorothy, the woefully innocent backyard gardener, saunters out to her perfectly prepared raised bed and plants a few zucchini and crookneck squash. This is her first new garden since she moved south, and she is looking forward to the long growing season. She plants very few because she doesn’t want to be overrun!

Back in Kansas, she grew more squash than she could consume every summer. What little Dorothy doesn’t know is that she isn’t in Kansas anymore. She’s headed for a high noon Texas-style showdown with the squash vine borer, Melittia cucurbitae. We’ll let her enjoy the beautiful spring weather as she watches her healthy plants get big and husky and more splendid every day.

After several weeks the first male blooms come on. Dorothy is getting ready for a big harvest, and she even digs out her old favorite recipes so that she’ll have something to do with all this squash. Right after a tremendous rain, she sees the bees moving around from one big, fat female bloom to the next. Holy cow! Our friend is imagining big bowls of steaming squash within the week. Then on Saturday, with dreams of crookneck dancing in her head, she grabs her trug and heads out into the sunshine.

Read more: How to Use Squash Pits for Bigger Garden Yields

A Rude Awakening

But, what does she find? Her composted, fertilized, well-watered, weed-free beds look empty. Her gorgeous squash plants have totally collapsed, and lay dying on the liberally mulched soil. This is ridiculous! It simply cannot be! Then she remembers the old hippies down at her local garden center who offered to help her out if she ran into trouble. At the time, she thought she wouldn’t need their help, but now she isn’t so sure.

The death of her squash plants could have been caused by some weird soil fungus, or all those crazy pill bugs crawling all over the garden bed. Oh no! Could it be those damned fire ants that sting the @#$%&*! out of her all the time? She can’t be sure why this happened, and she needs a bag of potting soil anyway. So, she grabs her dog Toto and heads out for the garden center to get some answers.

Beat those fire ants: Natural Fire Ant Control

Veterans of the Borer Wars

As Dorothy pours out her tragic story, the smiling woman behind the counter nods knowingly. Yes, indeed, these are the signs of the dreaded squash vine borer. It’s a well-known pest down here in the South, and it is becoming more and more common all across the country. Dorothy doesn’t give up easily, so she asks for some ideas about what she can do to take care of the problem.

Squash vine borer moth

A Squash Cover Up

She learns that many gardeners cover their squash with lightweight row cover. You cover the plants to prevent the female borer moth from laying eggs on the stems of your plants.

When the first female blooms appear you open the row cover, pick a male bloom, and use it to gently pollinate the female flowers. Carefully close the row cover, come back tomorrow, and repeat the process. New squash blossoms show up every day, so you have to keep doing this until you have a nice crop of young squash to pick. Then, you keep doing this periodically for the entire growing season. Unless there are borer pupa buried in the soil underneath the cover, this should work.

“What! Wait a dog gone minute.” Dorothy can’t believe her ears. She really doesn’t want to spend all of her spare time pollinating squash blooms by hand.

How to make a simple cover: A Cheap and Easy Way to Extend Your Growing Season

Spray those Suckers

“What about pesticide? There has to be some kind of pesticide to kill these evil borers!” Dorothy’s demand is met with yet more nodding and smiling. The cheery expert from the garden center produces a container from the shelf, and hope returns.

“This is Bacillis thuringiensis. You can inject this into the hollow stems of the plant, to kill the larval form of borer that is eating the plant from the inside out. Go to the feed store and buy a syringe that is made for horses. Fill it with Bt and inject each of the stems on your plant.”

This is not the simple solution Dorothy had been hoping for. “So, has this worked for you?” she asks.

The joyful expert’s smile fades away, replaced by a quiet confession. “No, this didn’t work for me. I’m not sure why… maybe I missed a stem somewhere.”

Dorothy keeps pushing, sure that there must be some way to beat these bugs.

“Well, some people go out and coat the stems with Bt every day. That’s too much work for me,” the expert adds. “Some people just go after the grubs with a knife! It gives people satisfaction to kill the little grub worms, although you also have to kill the stem in order to find the grub.” Dorothy is losing patience. She is beginning to think that a visit to the Emerald City may be her only hope.

Don’t Retreat from the Borer Wars

We all know how this story ends: Dorothy goes back to Kansas. But, you don’t have to move away to a different state to grow squash. I found an answer that really works. It is a compromise, but if you battle the borer and you are looking for new tactics, you might give this a try. Let me explain:

The familiar summer squash is Cucurbita pepo. This species has hollow stems, and the leaf stems are also hollow. The female squash vine borer deposits her eggs on either the main stem or on one of the leaf stems. When the eggs hatch, the larva bore into the stem. The hollow space inside the stems is the perfect habitat for the borer larva to eat, undisturbed by predators. You have probably noticed frass (insect poop) near the point where the borer went into the stem. The point of entry looks like a pinhole on the surface of the stem. As the larva grows, enough of the plant gets eaten that the loss of tissue kills the plant.

Plant a Different Squash

Cucurbita moschata is a species of squash that does not have hollow stems. There are numerous excellent cultivars in the moschata species, such as Long Island Cheese Pumpkin, Pennsylvania Crookneck, Butternut, and most notably, Seminole. Named after the Native American tribe that cultivated it, Seminole is a large plant that is wildly prolific. It sets fruit so early and so often that the immature squash can be picked for the table all spring and all summer.

Experiment with picking the squash at different stages to find the exact time that works best for you. I have found that I like them best when they are about the size of a baseball. They will look a little like round zucchini. Production goes down during the hottest part of the summer, but the vines spring back to life to produce a fine autumn crop. If you leave some of the fruits to ripen, you will harvest lovely, small, orange pumpkins at first frost. These are the best keepers of any squash I have ever grown. I usually have many good sound pumpkins remaining when I am planting the next season’s crop. I have asked other gardeners to try this out in their gardens, and they have experienced similar results.

Read more: How to Cook with Spaghetti Squash

Victory at Last

If you are still looking for revenge for past heartbreaks, just stand back and watch confidently as the squash vine borer moth lays her eggs on your Seminole vines. The base of the plant will become riddled with holes, but none of the larva are able to take the plant down! You may lose a leaf here and there but the plant lives on until frost, when you are filling a wheelbarrow, and then another, with pretty little orange pumpkins. Even the pumpkins that are still green when picked will keep very well.

Maybe this year you will be the one who runs out of neighbors and friends to accept the surplus squash you have grown. If so, head on over to the local food pantry to share your bounty.

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This post was written by Anthony Tamayo


  • Mike63Denver says:

    God’s Goodies give both inner city street gangers and rural folk in the country the smarts to win.

  • Barbara says:

    Loved the humor in this one. Wizardly.

  • JJM says:

    Thanks – 1st year I grew squash I had too much Zucchini to give away. Subsequent years have been like Dorothy – promising but little reward. Will look for solid stem plants/seeds to try this year.

  • Great article! Thanks for the information on borer resistant squash species. I love squash and it is indeed disheartening to see your beautiful crop die before your eyes. Definitely going to check out the suggested varieties.


  • Stephen says:

    I use the beauty brushes that you buy at the beauty store. I dip the brush in the Bacillis thuringiensis, and then ‘paint’ the trunk and stems of the squash plant about every week. If it rains, you have to do it again quickly. My strategy is to have the Bt on the plant before the moth lays her tiny red-brown eggs. Once the egg hatches, the larva is exposed to the Bt as it tries to eat into the stem or trunk and thus dies. If I see the tiny red-brown egg on the plant as I’m brushing it, I knock it off with my fingers. Once the egg is knocked off the plant, it will die in the soil. If you do this, you’ll have a lot of squash.

  • d. henry Lee says:

    Keep a hand spray bottle with you and mix 1 tablespoon dish washing liquid per quart bottle. When you see the squash bugs, spray them with soapy water. In about five to ten minutes they will die. I saw this on a utube video and it works. Liked the article.

    1. Michael Ford says:

      Yeah soap’s great for squash bugs. These squash vine borers don’t infest the leaves though – they infest the vines from the inside out – so you can never see them to spray them!

  • Crystal says:

    My pattypan squash lasted for months verses the yellow or zucchini that made it about a week into production. Well the first year. The next year, my pattypan seeds turned out to be acorn squash. I need to start keeping my own seeds. I only tried it for one year, so it may have been a fluke.

  • Shannon says:

    Is there something that is similar to zucchini that has a solid stem? That’s what I am having trouble with!

  • Steve says:

    From what I understand, the squash bug hatches in the spring, lays eggs and dies, and the new eggs won’t hatch until next year. I could be wrong. So a good way to beat them is just to succession plant. Get the first loss out of the way – you’ll probably get a decent harvest before then – and in the meantime have a new tray of seedlings ready to transplant.

  • J. Owens Smith says:

    I have injected a mild solution of liquid Sevin in the stems of my squash, and it totally killed every one of the little grubs. The plants produced “tons” of beautiful Crooked Neck squash. But, alas, I dumped all of it into my mulch pile because I could not find any “expert” to assure me that squash produced that way were safe to eat! Can anyone who reads here opine on whether such squash are safe to eat? Many thanks.

  • Anne-Marie says:

    Hi Leslie, I just have to say up front that you are one of the best writers I have ever had the privilege of reading. I love a good story filled with know how and you did not disappoint! I feel just like Dorothy, I have tried many things, but strangely enough I never thought about compromising in this way. What I am doing is not permaculture it is perma-ridiculous. When I really think about it, most of my children don’t even like zucchini, in fact one of my more head strong boys walked up to the store with his own money and bought something else to eat one night when I served it. When I look at the big picture I am not at all sure it is worth ALL this effort for a couple of crook neck squash and green zucchini. I am going to order the exact varieties you mentioned and give them a try. I would love to put this on my blog, bloomwhereyourplanted.com If you have written a book or have a blog or other articles I would love to read them. I am of the belief that life and gardening need a dash of humor thrown in!

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