GARDEN TIP: Squash Vine Borers

Post last updated: August 13th, 2018

Frass made by squash vine borer

Squash vine borers attack the cucurbits — squash, zucchini and pumpkin. In my squash row, the borers are winning. Borers: 5; Mizz Chairman: 0.  So I did a little research on the WWW.

Borers get started when a wasp-like moth lays eggs on your plant. The moth has a black body with reddish orange markings, black and orange hairy legs and metallic green, transparent wings. The eggs are oval, flattened, dull red in color and1/25th inch (1 mm) in diameter. The eggs graduate to a 3/4 inch cocoon of black silk housing a brown, 5/8 inch pupae. Emerging from the cocoon is a fat, grub-like caterpillar. Absolutely gross looking, he’s about an inch long with a brown head and a wrinkled, cream-colored body. He will feed inside the stalk, eventually killing the leaf. Once the leaf is dead, it migrates to the main stem. Before long, the entire plant is a goner.

I found a number of suggestions for borer control hither and yon on the WWW. My italicized comments/opinions are included on the suggestions that just won’t work for me. Lots of good ideas in this list for my next crop:

  • Squash vine borers are in your soil now. Use a hoe, deep plowing or rototilling where your squash grew last year. Look for cocoons about an inch deep in the soil.
  • Plant a trap crop of their favorite food – Hubbard Squash – early in the season to alleviate pest pressure.
  • Companion plant veggies they don’t like – bee balm, catnip, dill, garlic, marigolds, mints, nasturtiums, onions, radishes, and tansy. I have to wonder if planting Society Garlic around the squash would help. The smell certainly repels me; maybe the borers would pack their suitcases.
  • Grow resistant varieties – Seminole squash or squash from the cucurbita moschata family or sub-family such as c. pepo, c. mixta, and maxima because the vines of this family are solid; trombocino, a butternut relative used as a summer squash; tatume (which tastes the same as zucchini); and zucchetta rampicante (summer c. moschata).
  • Growing squash vertically will not deter borers as eggs will be laid all along the vine and under leaves.
  • Mound dirt around the main stem and over vine nodes on the ground. Fertilize the mound. This will create secondary root growth which strengthens the plant in case other portions are killed by borers. After the vine has taken root at multiple points, the infected portion can be cut off without damage to the plant.
  • Stems can be covered with a barrier by wrapping the vine itself with strips of row cover, aluminum foil, cheesecloth, or nylon stockings to prevent egg laying. Really? I have enough trouble cramming my own fluffy flesh into a pair of pantyhose. I can’t imagine trying to stuff a vine with stems and leaves into nylons. I’ll admit to trying the aluminum foil one year but it was not effective. I didn’t know you had to wrap the stem all the way below the soil line.
  • Place floating row covers over your vine crops when they start to vine or when you first detect borer adults. Secure/anchor row covers to prevent adults from moving underneath it. Keep these barriers in place for two weeks.
  • Catch and destroy the moths when they are resting on the upper side of leaves in the early morning and at twilight. Seriously? Sit out there in the garden doing surveillance? Do I need a private investigator’s license for this?
  • Hand pick and destroy eggs before they hatch.
  • Insecticidal soap sprayed weekly will smother the eggs. Start with very young plants when it is easier to achieve good coverage. Insecticides must be applied before the eggs hatch. All insecticide applications should be done in the evening after bees have completed their foraging.
  • Vigorously wipe the stems every five days with damp cloth to wipe away eggs. Wiping with an insecticidal soap is even better. Yeah right. Like I’m going to whip out a rubber ducky and give my squash a bath.
  • Inspect each vine once a week. Look for holes in the vine or an orange colored frass that resembles moistened sawdust. Don’t wait for signs of wilting. By then, it’s too late.  Once the larvae are inside the plant, pesticides are not effective.
  • Organic pesticides – Bug Buster, a natural pyrethrin, Neem, Spinosad and BT (bacillus thuringiensis). Some sources said BT works, others said it is not effective because it can’t be applied to the parts eaten by the borer. You can find BT under the brand names Dipel, Thuricide and Green Step.
  • Synthetic pesticides – Bifenthrin, Carbaryl (sold as Sevin dust, spray, granules or concentrate), and permethrin.
  • Stagger squash plantings to avoid the peak egg-laying period or make a second planting of summer squash later in the season (check your gardening zone) after adult borers have finished laying eggs.
  • Surgery — cut a lengthwise slit in the vine, expose the borer, remove him, clean the area out and place soil over the wound. Obviously, not for the faint-of-heart. Just reading this suggestion nearly finished me off.
  • Murder — one source said to locate the borer at night with a flashlight. The light will shine through the hollow vines allowing you to spot the caterpillar and run him through with a toothpick. I can just see me out there with a flashlight tripping over a possum in the dark and sprawling face first into the squash.
  • Promptly pull and destroy any plants killed by squash vine borers. Remove all debris from garden site so borers can’t over-winter.

7 thoughts on “GARDEN TIP: Squash Vine Borers”

  1. I love your commentary but didn’t you already do a face plant in the garden? I’m just saying.

    1. Yes, I’ve done two face plants in the garden but one of them happened at night when I tripped over my Big Ohio Rock. I’m just as likely to trip over a possum if I was out there with a flashlight looking for squash vine borers. Quit harassin’ me.

      1. I can’t help myself. I’m surprised you didn’t whack your empty head on that Big Ohio Rock. For a gardner you sure have 2 left feet. I bet the other gardners who respond don’t face plant as often as you do and, before they weigh in, just for the record, Mizz Chairman hasn’t printed half the times she’s found herself up close and personal with the dirt. Oh, I’m sorry soil.

  2. Good tips! I can’t imagine actually doing half of those, as well! Though I did go all commando on slugs for several evenings last year outside with a flashlight, which did actually work. Having caught the great-granddaddy of enormous slugs as well as many little ones, I’m enjoying a great decline in the slug population this year. (That great-granddaddy slug had not been fooled by my beer traps, or he was large enough to get out of them. Now he will not sire any more baby slugs!)

    Good luck with your borers! Nasty bugs.

    1. Hi Indie — Thanks for stopping by. I actually found a couple of slugs oozing across the yard in broad daylight. I stomped ’em as good as I could. Don’t know whether I actually squished the life out of them or just gave them a major back ache. Hard to say. As we approach the middle of June, my garden is definitely on the wane. Time to start tearing stuff out.

      1. HOLY TOLEDO, Meta, that post just went up! You must have been sitting in front of your email screen. No, the bottles are a cumbersome 18 ounces. I should have mentioned that. The bottled water I used to buy is 16.9. I have ONE left for water-on-the-go. I have been shiftless this week about posting…

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