Defeating the Squash Vine Borer – FINALLY!

Every spring, after a long, cold, dark winter has washed away any memories of the prior growing season’s trials, I awaken hopeful (and naïve?).  Despite my husband’s warnings, and probably my better judgement, I persist in planting zucchini in my garden.  Sure, I know that zucchini has the unfortunate reputation as being overgrown – there’s even a National Sneak Zucchini On Your Neighbor’s Porch Night (August 8 for those who like to plan) – but in my Maryland garden, attempting to grow zucchini can often bring heartache and pain.

Why?  Because THIS:

Squash vine borer adult
Adult squash vine borer (U. Md Extension)

Lays pinhead size eggs on the stems of my plants that hatch into the larva of which hatch and proceed to feed on the vines…

squash vine borer damage

…thereby destroying the vascular system of the plant from the inside out before you can say ‘where’s my zucchini bread’?

Heartbreaking!  (To add insult to injury, the overblown worms burrow into the soil where they  hibernate until they emerge as adults the next spring to start the cycle all over again.)

The Season Begins

In 2019 it all started when I planted my garden the traditional Mother’s Day weekend (in Maryland – check your local listings!), and soon after my baby zukes emerged.  Everything was going very, very well until my husband and I were getting ready to leave for a week-long vacation in mid-June.  As we were out the door, he exclaimed:  ‘I think that’s a squash vine borer on your zucchini plant!’

This news literally sent me into a frenzy because I thought it was too early in the season to start having to deal with this pest.  Instead of getting on the road (ironically we were on our way to a Master Gardener convention!), we spent the next 20 minutes:

1. Literally trying to catch the bugger in a butterfly net and
2. Inspecting all the vines and stems for those pinhead size eggs I mentioned.

We failed in catching the moth, but I did destroy about 15 or 20 eggs, sure I did not find them all.  Resigned that this was the best we could do for the moment, we hung up our nets and got on the road, hoping that not too much damage would be done in our absence.  This battle, after all, waits for no one, and we must be ever vigilant to thwart attacks.

Zucchini plants
(Nice & Healthy) Zucchini plants upon return from vacation

Fast forward to our return the following Friday evening.  Nicolas again spied an adult moth (was it the same one?  We’ll never know.)  THIS time he caught it!  Oh the joy and relief!!!  I did another cursory inspection of the vines and stems, but really didn’t find a lot of eggs, and that worried me.  What were ‘they’ planning?!?

Still, the next week or so was relatively quiet as I started seeing bright, yellow flowers emerge on my plants.

But oh no!  Only female flowers!

Zucchini male and female blossom
Courtesy of ‘Mountain Plover’


Trouble in Paradise

Much like people, there are male and female zucchini flowers.  The females won’t grow a zucchini unless they are pollinated by a male.  It’s possible to hand-pollinate the females (which, not surprisingly, I’ve been doing just about every day since late June), but I couldn’t do that until male flowers emerged.

As a result, several of the early ladies had to be ‘sacrificed’ because of lack of a ‘mate’.  Woe is me!!!


First zucchini 2019
First zucchini of 2019, on June 23!

Once the flowers got themselves together (some with the help of my pollen-laced Q-tip), I started getting real zucchinis right and left!  It was heaven, and while zucchini pie, zucchini bread, grilled zucchini, and more zucchini bread abounded, there were seemingly no squash vine borers to be found.




My husband texted me the following photo on July 8:

squash vine borer egg
Squash vine borer egg, July 8, 2019

The Battle Begins

See that tiny egg?  NOOOO!!!!!!!!!  The squash vine borer was BACK and hard at work.

This, too, sent me in a frenzy that evening, which got me out in my zucchini patch, knife in hand.  You see, once the eggs hatch you can sometimes see the worms in the stems as evidenced by the sawdust-like ‘frass’ that will be coming out of an infected stem.  That night I cut out several worms – catching them ‘just in time’ before they did too much damage.  I was on a mission – defeat is not an option!  (I was so stressed out I failed to take any photos during my worm-hunt.  Just as well, as the results would likely have been ‘graphic’, not for sensitive audiences.)

Since then, I continue to check my plants daily for additional signs of worm damage, eggs, and, other pests such as squash bugs and various fungal diseases.

After winning a few rounds of ‘peek-a-boo’ with hungry, hidden worms, I haven’t found any additional damage to my plants in over a week.  Did I dodge the bullet this year, finally?  I dare not say.  But here is what my plants look like to date, which for me, is unprecedented this late in the season.

Zucchini plants

Anybody want some zucchini (bread)?

Zucchini bread
Donna’s ‘famous’ zucchini bread

For more information on how to win the battle:

For those on a similar mission to defeat this pest the natural, if obsessive, way, here are two resources that provide excellent information on how to expel this pest from your garden.  My home state’s University of Maryland Extension squash vine borer page, and the University of Florida, which has a bit more scientific information about the life cycle and habits of this pest.

Good luck!  Feel free to share your own experiences here.

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