On 8 Dec 2011, at 16:49, Robert Hoel wrote: > The concept behind diatomaceous earth is that the very fine particles are like > glass shard and the critters that crawl through it have there little bodies > sliced to shreds. Wherever you read that, it is an exaggeration and a misunderstanding of the mechanism by which diatomaceous earth kills insects. In the simplest analysis, insect exoskeletons are composed of chitin with a waxy layer on the outside to prevent water loss. Diatomaceous earth abrades the waxy layer leading to uncontrolled desiccation and death of the insect. A far cry of being sliced to shreds, though both lead to death. PS: Digging into Wikipedia, I find a link to http://home.cc.umanitoba.ca/~fieldspg/fields/… which asserts that diatomaceous earth _absorbs_ the waxy layer, as opposed to _abrading_ it. I do not know which explanation is correct. -- Rodger Whitlock Victoria, British Columbia, Canada