Diatomaceous Earth
Doug says
That's an interesting question and the answer is generally "no".
The notion that it was possible was touted by Jerry Baker but like many things this man proposes, the reality is somewhat different. (I note if you're a Jerry Baker fan, that his gardening advice is often pretty worthless and when it comes to the way he sprays Dursban over everything - downright dangerous.)
The deal with Diatomaceous Earth is that pesticide quality DE is usually over 97% amorphous silica. The average DE is composted of 86% silica.
The DE for pools is heat treated. This causes it to lose it's shell or "amorphous" shape and assume a crystal shape that is excellent for filtration.
Does this crystalline shape still work for insect control?
Ah, that's the question isn't it.
The consensus seems to be no that it doesn't. The heat treatment eliminates the microscopic sharp edges and turns it into crystal-sponge shape able to block the passage of small particles of dirt. And certainly not an insect-killer in the same class as the 97% amorphous crystals.
That's the best research I can give you at this time. Should something come to my attention in the way of other, real information, I'll pass it along.
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