Squash vine borers!
Of all the garden pests I’ve encountered, this critter has been the most destructive. I’ve planted acorn, zucchini, and yellow varieties of squash and also pumpkin twice in the past three years. My yield? A BIG FAT ZERO!
The first year that I planted squash and pumpkin I was eager to have a good harvest for eating and for pumpkin carving. My garden had done well and produced everything else I planted in abundance, so why shouldn’t the squash and pumpkin, right?
Because of the squash vine borer!
This flying menace is mega-destructive and very difficult to rid or kill. On a hot June afternoon of that first squash planting year I noticed a flying insect that I hadn’t ever seen before. At first, I thought it was a wasp because of its flying characteristics and the buzzing sound. I noticed that it was particularly interested in my squash and pumpkin plants, but I didn’t want to kill it before I knew what it was. An avid gardener knows that there are many beneficial insects in the garden.
After some quick research, my panic mode kicked in. Surprisingly, this bug is a member of the moth family … but that’s where the similarities end. This winged, garden bane flies like a wasp during the heat of the day instead of in drunken circles at night like a normal moth.
The adults emerge in late June from cocoons in the ground. The females lay eggs on the underside of leaves and the larvae emerge about a week later.
These larvae then bore into the stems of your precious squash vines and start munching away. As they fatten up on your investment, they block the water flow to the rest of the plant. That’s why the first sign of them is severe wilting. After about 4 – 6 weeks, they burrow into the soil to pupate and return the next summer.
An advanced sign of their presence is an excretion from the stalk of the plant, called frass. Disgusting. It’s a yellow-orange colored ooze that, from a short distance, resembles sawdust. Once you see this (like I did) the game is pretty much over.
I battled these larvae that first year, using a pen-knife to cut open the stalk and kill them. It was too late by then. My plants were decimated. I skipped planting squash and pumpkin the next year. I tried again the following year and, again, the horde returned. I didn’t do battle with them that time. When I realized what I had, I just pulled up the plants and trashed them in order to keep the larvae from returning to the soil.
There is no reliable way to kill the larvae once they’re in the plant. Take it from me … if you see the frass, just pull up the plant and dispose of it in the trash (not the compost!). More than one larva can attack a single plant and you’ll slice and dice your plants trying to remove them until you’re exhausted and still lose the plant anyway.
There is good news on the battle front, though. If you’re able to put in the time and effort, you can prevent the eggs from being laid in the first place.
To start, place a yellow container of water (apparently the squash vine borer’s favorite color) in the area of the plants. Check the container daily for drowned or drowning perpetrators. When you see some, it’s time to take further action.
I’m not going to mention some of the chemical remedies that are marginally effective because I try to practice chemical-free gardening. But, row covers are a good next step. Keeping the plants netted will prevent the adult fliers from being able to lay eggs on the leaves. Make sure that the covers are secured well enough to keep the borers from getting underneath. Just keep in mind that if you have flowers on the plants, your pollinators won’t have access either. Pollination will be up to you.
Keep the plants covered for at least two weeks after seeing the first adult borer. After that amount of time, their laying period should have ended and the threat gone.
Another plan (and one that I intend to implement) is to wait until after the first week of July to plant. Typically, a second planting of summer squash will not mature until after the egg-laying season of the squash vine borer has passed. Since I live in a hardiness zone where I can enjoy gardening well into October, this seems like the least labor intensive way to defeat the pests.
I hope that you never see in your own garden one of these nuisances illustrated here. But if you do, I also hope that some of this information will help you to preserve some of your crop. Good luck in squashing those buggers! … (pun intended).
Thanks for reading. Wishing you happy and healthful gardening.