My War Against the Squash Vine Borer

Photo Credit: G.K. Gerber on bugguide.net

The past two summers, I tried to grow zucchini and squash in my garden; but I harvested very little before the dreaded squash vine borer attacked and killed my plants. People who live here either use pesticides like Seven dust or just give up. Pesticides are not an option in my garden, and this Italian refuses to give up! So, this year I’ve declared an all-out war on the Squash Vine Borer.

WHAT IS THE SQUASH VINE BORER?

The scientific name for the squash vine borer is Melittia cucurbitae. See the word cucurbit in the name? Its very name screams, “I’m going to kill your squash!”

The squash vine borer, or SVB, is a moth that lays its eggs at the base of squash vine stalks. When the eggs hatch, the caterpillars burrow into the stalk and eat the inside of the vine – thus, killing it.

Zucchini killed by the squash vine borer last June

Zucchini killed by the squash vine borer last June

The larvae then burrow into the soil, wrapped in a cocoon. Here in the South, the first generation (we get two – aren’t we lucky?) emerges as moths in late spring/early summer, usually around late May, and lay their eggs on the squash. And the cycle begins again.

After two years without getting oodles of squash for all my summertime recipes, I’d had enough. So, I did some research on how to combat this fiendish pest.

HOW TO COMBAT THE SQUASH VINE BORER

1. CROP ROTATION: Because the SVB cocoons in the soil, crop rotation is a must. It can’t stop the adults from laying eggs on your squash that’s elsewhere in the garden, but why serve up a meal to them on a silver platter? I rotate all my crops every year, so this wasn’t a new thing for me to try.

2. ROW COVERS: If you cover your squash during the time that the adult SVB is looking to lay her eggs, she can’t get to your squash. However, you will have to remove the cover when the female flowers bloom or hand-fertilize your squash. With my schedule, that’s not an option for me.

3. CHOOSE RESISTANT SQUASH: Squash is part of the cucurbit family, but there are more than one species of squash. The four most common species are C. pepo, C. moschata, C. maxima, and C. mixta. Of all the species, C. moschata is the most resistant to the squash vine borer. Unfortunately, most summer squash is of the C. pepo species. However, I did find an Italian variety of squash that is C. moschata – Tromboncino squash! All but one of my squash varieties are from the C. moschata species this year: Tromboncino, Burpee’s Butterbush, White Acorn, Black Futsu, and Seminole pumpkin. I do have one C. pepo variety – Tondo Scuro di Piacenza – which is a round zucchini. It’ll be interesting to see how vulnerable it is compared to the other squash.

4. PLANT EARLY OR LATE: The goal is to not have a meal of squash ready to go when the SVB is ready to lay its eggs. I chose to plant “early” by planting transplants rather than direct sowing. I just added seeds to my germination station, and they grew quickly. In fact, many of the squash produced male flowers before I even transplanted it!

White Acorn squash flower (male)

White Acorn squash flower (male)

You can also plant later in the season, after the SVB lays its eggs, so it misses your crop altogether. (I’ll have a fall crop planted in August, yet then I’ll be battling pickle worms and powdery and downy mildew. But I digress.)

5. PROTECT THE SQUASH VINE STALKS WITH COLLARS: I read that putting collars around the base of the squash vines helps prevent the adult SVB from being able to lay her eggs there. I also read that the color silver disorients insects, confusing them as to what they’re seeing. So, I combined those two facts and made collars for my squash and pumpkin out of heavy duty aluminum foil, shiny side out. I folded the piece in half, then in thirds to make a three-inch wide strip. I pulled the soil away from the base of the plant and wrapped the foil around the stalk, loosely enough to let the plant continue growing. I then put the soil back around the base of the collar. I’m not sure if I did it correctly, but we’re going to find out soon enough.

Squash with aluminum foil collars

Squash with aluminum foil collars

Even the tromboncino squash in the pot under the teepee trellis got collars.

Tromboncino squash with aluminum foil collars

Tromboncino squash with aluminum foil collars

As you can see, my squash are dressed for battle, and I’m determined to see that they win! I’ll keep everyone posted as to how the war goes.

If you’d like to read more information on fighting the war against the SVB and other squash bugs, see “Squash Bug and Squash Vine Borer: Organic Controls.”

Do you have the squash vine borer where you live? How do you fight it?

Happy hunting,

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6 comments on “My War Against the Squash Vine Borer

  1. I tried the collars one year..maybe 50 percent assist. Now, Inplant early and you can cut them open and kill the larvae and then rebury. The plants actually stand up to it. Resistant varieties of course being the easier option, but I love my heirlooms too…

  2. Johnny’s seeds offers a self pollinatig zucchini. I started the seed indoors and am now growing it under a row cover in my SC garden. Last week I harvested 6 small squash from 6 plants. Today, 4 six inchers. So far, so good. I am also growing a specialty yellow squash under row cover. That one I hand pollinate every morning. I should be harvesting that any day. I tried the foil collars last year, but they didnt work for me. Hope you have better results!

    • I did plant the resistant species, so we’ll see how it goes. I’ve got female flowers on many of my plants now. I also have a couple of white acorn squash that look as though they were fertilized, so they should grow. (They’re a bit bigger than the ovaries on the female flowers.) I’ll keep everyone posted how my squash does in my weekly updates on Mondays. Glad your squash is doing well!!

  3. I just learned about this borer. I found out because it has killed all of my squash, zucchini, and I am losing pumpkins and cucumbers now. Two different raised beds about 20 feet apart. We sliced the few remaining plants and got the worm out. I pulled all dead plants, and mostly dead. I think I am going to turn the two beds before fall and put in some new compost in. I planted mothers day weekend plants that I started inside months before. I do not remember seeing this moth ever.

    • They are nasty! I don’t know where you live, but here in the Charleston, SC area they are rampant. They come out in May, laying their eggs. By June, the plants are dead. I will say that starting them early and putting aluminum collars on them helped. I also found that the c.pepo family (like zucchini and yellow squash) succumb easily to the borer. However, most of the c.moschata that I planted survived. All my white acorn squash died and half my butternut plants (both were c. moschata); all of my black futsu squash and seminole pumpkin survived.

      As for the cucumbers, the borer leaves those alone. You may have pickle worms…which I have. Pickle worms usually don’t come up from Florida until end of July, beginning of August. However, this year, they came the beginning of June! Probably because of the early intense heat. They drill holes in cucumbers and melons, and you can often see the fruit “sawdust” on the outside of the hole. Yuck. If your cucumber vines are dying, it could be because of a cut worm or something.

      I guess we just have to plant better varieties, keep our plants as healthy as possible, plant more than we need so we don’t feel badly about losing some fruit, and use organic methods of control when needed.

      Though I would like to eradicate the squash vine borer forever! 🙂

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