Monday, July 13, 2009

Battling the squash vine borers

Before Hurricane Ike, our garden was a butterfly habitat. We had host plants for butterflies to lay their eggs, and nectar plants to feed them. For years, I brought caterpillars of all types into the house to watch their amazing growth and metamorphosis, much to the delight of our sons and David's disgust. Only a few escaped, but David still hasn't forgiven me.

Ike knocked down our fences, a few trees and our carport. Large parts of the garden were wiped out. Some plants returned, but the weeds quickly gained the upper hand. We finally gave up trying to restore the old garden, and decided to clear out everything to start a new garden devoted to vegetables. We still have lots of host plants. To name just a few, we have milkweed for the monarchs, bronze fennel for the black swallowtails, a lime tree for the giant swallowtails, passionflower vine for the gulf fritilaries, and a hackberry tree (missing it's top thanks to Ike) for a slew of butterflies including the question mark and hackberry emperor. And that's just the short list.

The intention is for the vegetables and butterflies to happily co-exist. Butterfly caterpillars for the most part limit themselves to eating plant foliage, rarely inflicting anything more than cosmetic damage to the plant. However, the vegetable garden has forced me to expand my expertise beyond butterflies to include at least one moth: the squash vine borer.

Never have I so hated an insect. Before I knew what had happened, all our zucchini and squash plants suddenly flopped over. The huge, beautiful green leaves started to yellow and die. And the abundant flowers produced not a single zucchini or squash. I mourned the loss of my Cocozelle, Costata Romanesca and Lungo Bianco zucchinis, and researched extensively to discover the cause of their death.

At first I suspected a disease, but soon learned that the culprit was the squash vine borer. Unlike my beloved butterfly caterpillars which limit themselves to eating leaves, the squash vine borer caterpillar hides inside the stem of its host, making it invisible to the gardener. And as it eats and grows inside the stem, it eventually weakens and kills its host.

I read that some growers cut open the stem and remove the caterpillars. I attempted this, and actually found two caterpillars. They were fat and happy inside the stems of my zucchini. Unfortunately, I'm not known for my knife skills, and while I killed the caterpillars I also caused catastrophic harm to my already weakened plants. I felt like Bill Murray in Caddyshack trying to defeat the mole destroying his golf course -- the caterpillars may be gone, but so are my plants.

I don't have any more zucchini plants right now, but I do have several Benning's Green Tint squash plants started from Southern Exposure seeds. I have developed an improved technique for killing the caterpillars. I use a cake tester to stab through the stem anywhere I detect a hint of caterpillar frass. The picture shows the holes I've made in the stem of one plant. The big split is where the caterpillar was living inside the stem. Amazingly, the plant is still quite healthy and flowering profusely. Don't worry, I don't use the cake tester for baking.

I now spend each morning and evening searching for eggs, and handpicking them off the stems, leaves and even flowers of my plants. I have caught the moth lurking in my garden several times, but so far I haven't been fast enough to catch her. All this effort makes me wonder how much I really like zucchini and squash. Is it worth the effort? If I ever manage to successfully harvest a zucchini or squash, I'll let you know.


  1. I lost my plants this week to the dreaded squash vine borers and I was thinking the same thing. Is it really worth all the effort? I could buy organic zucchini and save myself a lot of work. :)

  2. Thank you for this blog on the squash vine borers. Now I know. What a shame. I already pulled up the squash (but replanted 3 more that just sprouted yesterday) and now my zucchini is suffering greatly and trying ever so desperately to grow 2 half grown zucchini babies. All the leaves looked dead today so I think it has bit the dust as they say. I will watch my new squash plants carefully for this bug!


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