Tales from the Garden: Squash Vine Borer

My summer garden suddenly took a turn for the worse when I noticed some sudden yellowing of the leaves.

squash plants turning yellow

At first I thought I might not have been watering enough (it's been hot, dry summer up to this point). So I increased my watering, to no avail. Then, after some internet research I began to think it might (hopefully) be a nitrogen deficiency; or, possibly an iron or zinc deficiency.

I read that if the basal leaves turn more yellow than the leaves closer to the shoot tip, that it could be a nitrogen deficiency. But, if the leaves are more yellow away from leaf veins and have more green near the vein, then it could be an iron or zinc deficiency.

I thought (hoped) the deficiency could be caused by over watering. I read that over watering can leach the minerals out of the soil. So I cut back my watering, to no avail. That's when I began to explore the more bleak possibilities of why my squash plants are turning yellow.

So I went out to look for signs of frass; frass is a tell tale sign of the dreaded squash vine borer.

Squash Vine Borer Frass

The troublesome squash vine borer (Melittia satyriniformis Lepidoptera: Ageiriidae), is actually the larvae of the adult squash vine borer. The adult moth, which is often mistaken for a wasp, lays dark reddish brown, disk shaped eggs at the base of the plant. When the eggs hatch, the larvae (which are whitish, wrinkly, brown headed worms) burrow into the plant stem and essentially eat the plant from the inside out; leaving behind a wet sawdust looking substance which is the frass (squash vine borer poop).

I read that there really isn't much hope if you discover the squash vine borer after it has done much damage to the squash plants. About the only cure at this point is removal of the insect. You slit the vine open where the insect appears to be and hope you find it. Once you find it, you remove and dispose of it. Then you cover the damaged area of the vine with fresh dirt and hope for the best.

So I decided to slit a vine open to look for the squash vine borer.