I woke up at 6 a.m. on a recent morning ready to conquer. Equipped with garden gloves, a spray bottle of organic Bt, a fly swatter, and a vengeful heart, I was determined not to lose my grapevine this year. Just yesterday I had identified the dark blue moths dancing amid my garden to be Grape Leaf Skeletonizers and had formulated my plan of attack.


I started my mission with the fly swatter. With a Clint Eastwood stance (and squint) and an old Western whistle escaping my serious demeanor, the showdown began. Any smarmy little bugger I saw battin' around out there faced a certain doom. Grape leaf skeletonizers are fairly slow creatures and swatting them right out of the air become my new favorite game. I also noticed many of the moths seemed to be dying; laying on the leaves and barely flinching when I came near. Perhaps they die immediately after laying eggs? If so, it serves them right.

Then came grapevine care. Thankfully my vine is still young and therefore easily managed. I overturned the leaves one at a time. Yes, every one of them. One thing I noticed is that the newest growth never had any eggs. But dozens upon dozens of the mature leaves were covered in clusters of eggs. This is where the gloves come in - I methodically smushed every cluster I found. Grape leaf skeletonizer larvae can irritate the skin but their eggs generally do not. I wore the gloves to pick off any caterpillars I might have found but it came in handy with the smushing too.


Then every single leaf got a thorough coating of Bt. I diluted approximately one teaspoon of Bt concentrate into a 32 oz spray bottle and went to town on the front and back of each any every leaf. Bt, short for Bacillus thuringiensis, is a naturally occuring soil bacteria that attacks the stomachs of those leaf-eating menaces. Within a day or so of ingestion, caterpillars stop eating and die. Aah, sweet justice. The awesome thing about this product is that Bt doesn't affect other insects or beneficials. I like to think of it as a natural predator of caterpillars. The downside of Bt is that it only works on larvae, not the grown moths or their eggs. And I've never had it work once the larvae (caterpillars) were bigger than a grain of rice.

Reapplication of Bt should be done every 14 days or after it rains. My only concern is whether our high summer temps will inhibit effectiveness of the bacteria. I also have no idea if these moths attack other plants, although I've seen them on nearly every plant I have. I believe the moths feed on nectar rather than leaves, so perhaps my entire yard doesn't need a thorough coating of Bt, although the idea is rather tempting. I did spray my tomato plants to help in our efforts against the tomato hornworm. That, coupled with our friendly parasitic wasps, should do the trick nicely, although I'll keep an eye out (and a fly swatter ready) for any signs I can help.

Tara lives and learns with her family in Las Vegas, NV. You can read more of her at TheOrganicSister.