So the question for me now is this: does it matter if it is food grade or not? Well, all the sellers on the internet seem to think not. I may do another experiment, but I doubt it works and it is expensive. Besides, there is some controversy over whether or not DE harms earthworms. I also wonder what affect the stuff would have on beneficial organisms and bacteria.
Can anyone out there shed further light on the issue?
For a list of all of my slug control experiments, please see this page.