On squash vine borers

P1000544Uh oh!  Trouble in squash paradise!  Amish Pie Pumpkin looking peaked

If your squash plants appear perkily green one day and wilted and yellow the next, a squash vine borer might just be your nemesis.  This year has been a productive one for squash vine borers in my garden, so I thought I would show you the signs–and maybe cures–to slow down this pest’s rampages.

The adult moth, which looks something like a red-legged wasp, lays its eggs on either the base of a leaf or the base of the plant’s stem.  The larvae, then, either chew their way through the leaf stem and down to the base of the plant or they just have a prime banquet at the base.  So, one way to prevent the moths from laying is to cover the plants until they start blooming (most squash plants rely on insect pollination and need to be uncovered).  This works fine for small summer squash, but for me, well, my 30′ long pumpkin vines are really not going to be covered in row cover any time soon.


Crap!  Frass!  (But frass IS crap…) Plus, the stem is no longer green; all bad signs

So, I remain vigilant, checking the stems (right about where they go into the ground) for frass (the chewed pulp of the stem:  it looks like sawdust) and for squishy spots.  Out comes my utility knife and a piece of wire.  I cut the plant where I find the hole or the soft spot, and I excise the larva, hopefully whole for the chickens, or squished up with the wire if it’s in an impossible spot.  I make sure to run the long way with my cut (that is, in the direction the plant is growing:  like a tree, most of the moisture flows around the outer diameter of the stem) so I make sure my cuts are vertical, not girding it at all.  After surgery, I bury the whole area where the stem was cut, add more compost to the roots, and water the plant well.

P1000551Little white grubby-looking larva:  this stem was a veritable nursery school of them.  I don’t know if it will recover.

Another thing I do is to make sure the vining plant has more than one rooting spot, so I bury the growing canes anywhere they hit the dirt:  the plant won’t die this way if it is really struck hard by the borer.  Most vines will do this by themselves, incidentally, but it’s nice to help them out.  Another trick I have heard about but not practiced is to wrap the base of the plant in tinfoil to discourage the wasp from laying.  I am not sure this would work, so my roll of tinfoil remains in the pantry.

The one bad thing about my method is it’s not exactly proactive, it’s reactive.  With the exception of burying the branching vines, it’s a daily diligence to verify the borer’s presence.  Another thing on the task list, that is.  But that’s okay.  It’s gainful, rather gross employment!

15 responses to “On squash vine borers

  1. This was our first year getting hit by them. Don’t know how I went past years unscathed! Lost a few before I learned to do what you said and I haven’t lost another plant this year to them. Amazing how resilient plants can be. Cut down the stem, worms removed and covered back up and then comes back full force? Amazing to me.

  2. Thank you thank you 🙂

    I don’t think I’ve had them before either–or at least not until late in the season when I no longer cared if a zucchini would ever appear again….

    I did somewhat try this with my zuke, but the whole stem started disintegrating when I examined it (too late I guess). The covering up the stem part is what I missed from previous instructions and will be a big help. And the pics are super useful too.

    I read the tinfoil thing too and tried it on a couple of remaining younger plants, I figured what the heck?

  3. The varmints are pure *EVIL*.

    Thank you for your wise words as usual! My garden is in a sad state this summer due to my general apathy and tendency to NOT like bending over these days. 😉

    I’ve got some lovely pie pumpkins going nuts out there (they decided to climb a nearby fence of their own will), but just yesterday I thought their leaves looked a bit wilty–Darn vine borers, I thought to myself. I’ll have to have a better look tomorrow. I’m hoping they were just thirsty and today’s rain will have perked them up.

    The yellow squash and butternuts are still looking good. Fingers crossed.

  4. Oh ugh. I’ve heard about folks squirting some sort of product right into their stems, but your way is the tried and true way.

    I wonder — if you routinely pre-buried the stems, would the wasp just lay farther along the stem? or be discouraged? I wonder.

  5. Thank you! I admire how you handle the pests and destroyers in the garden, keeping along and doing what you can, rather than throwing up the hands (as I nearly did this year with my peppers….but am glad I didn’t). I hope that you can rescue most of them.

  6. Thanks for the info. I am really enjoying your blog. We live in the cental valley ca and I have issues with spider mites. Any thoughts?

  7. Kim, glad to hear you’ve been able to rescue a few. You know, I haven’t had them much in the past either, or if I did get them, it was when I was REALLY tired of that zucchini or summer squash so I was happy it up and croaked. But yeah, they’re really resilient.

    Sara, yeah, unfortunately, zucchini isn’t one of those that will root itself elsewhere, so it will be toast. So glad to learn you found the tutorial useful; sorry it took me so long to get posted, and I ended up taking the photos myself because SOMEONE was too busy. Harrumph. Oh well.

    Amanda, during and after pregnancy I had horrible acid reflux and vertigo so picking something up off the ground became a challenge. You should’ve seen the contortions I would go through to load the dishwasher! SO indeed I can imagine how “fun” it is to garden, and you’re pretty far along! I remember putting up about a bushel (!!) of beets when only 4 months pregnant and I thought I was going to have to go into a back brace.

    Yeah, Stef, that’s why the foil remains in the pantry: they’d go further up, I figured. I am not so sure about burying the thing up as it grows; the way it grows is the way it expects conditions to be so…maybe just doing the burying selectively is the best action. If you have borers that is.

    MC, I never throw up my hands! Okay, maybe with weeding, but not with pests. I try to exercise all organic options before the plant goes into the burn pile.

    Brooke! How odd, I thought that mites were an indoor plant problem. You would have to google a solution, as I would think spiders were good things. Sure that’s what they are? Aphids can look similar.

  8. I’ve had the nasty things every time I grow squash. I saw a male in the garden about a week ago. I tried to catch it but was unsuccessful. I’ve given up growing anything but C. moschata (which is resistant) and zucchini which is usually so prolific it is worth growing before it dies. Sadly it is not a good squash year. Maybe next year.

  9. so, any wisdom on squash bugs? after further investigation, it seems we are struggling with these, not squash vine borer. which is discouraging, because it seems there’s less we can do.

    • Ah, I hate those things.

      Every morning, look for clusters of eggs hiding under leaves or on leaf stalks. A plant can usually handle the infestation of one hatched cluster, but two spells doom. Squish the eggs and any adults you can find: in the a.m., the adults are moving pretty slowly, and can usually be found below the base of the plant. Nothing kills or discourages the adults, alas. I have read that if you put a piece of cardboard near the base of the plant, the adults will hide under it: lift it up and have a squishfest!

      Their primary target is Yellow Crookneck squash, then all the other summer squashes, then the pumpkins, then the butternut. Some varieties are more resistant than others

      • thanks for the tips. i keep hearing that squash bugs like yellow crookneck and pumpkins; however, ours have left those alone (in favor of the uncle david’s dakota dessert squash nearby). the butternuts and pumpkins are next, though.

        i try to catch them, i do, but every time i go out i only get a couple. judging by the sad death scene out there, there are dozens more that i’m not catching. i need squash bug goggles, or something.

        between these and the tomato hornworms, i’m just dying out here.

  10. The vine borers waited until the hotest days of the year to strike this time. By the time I caught on to what was happing I had lost all of my vines. I don’t have much space to grow in so I trellis all of my vines. Next year I’m going to find enough space to let the vines root in more than one spot. I hope it helps.

  11. Wow. Thanks for sharing this information. My squashes were taken out 2 years running by borers and I had no idea what to do other than douse the plants with toxic pesticides. I don’t like using those kinds of toxins on anything, let alone plants I use for food, so my squashes all died. Next season I will know what to do!

  12. Yep, those squash vine borers shortened the life on my crock neck and summer squash. I still got a lot before they died, but I sure don’t like those borers. A friend at work gave me a squash to eat and also plant the seeds. He said the borers do not bother them. He was correct. These squash are pretty amazing. They have a really hard stem and vine that is solid. The squash start off round or sometimes elongated. They are light green when about the size of a tennis ball and then they start turning darker green. I like them best small and you can cook them just like the yellow crock neck or summer squash. They taste just as good. When they turn darker green you have to cook them longer because the skin is tougher, but they taste about the same. If you leave them on the vine long enough they are like a butternut or winter squash. They turn yellow to orange and look similar to a small pumpkin. They keep a long time like them in the pantry. I cut them in half, remove the seeds and bake them like a butternut. They taste good enough without seasoning. I will try to find the name of them.

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