Does anyone have a recipe for nontoxic garden dust for plants? [View all]

I hate to resort to something like Sevin and the organic spray stuff isn't doing the trick for my kale plants. I'm not even sure what's eating the leaves, but I suspect it's the early stages of cabbage worm. For some reason I've always had better luck with dust rather than spray on kale. I was thinking of something maybe flour based or cornstarch based. Any ideas?