Nope, this isn't me powder sugaring my garden as sweet as gardening is.
This is me using diatomaceous earth to cut some bad buggies up.
Diatomaceous earth, while looking delicious and dessert-like (or like a particular drug I suppose...FLOUR, of course! Those darn addictive carbs...) is actually sharp and lethal at the microscopic level to slugs, snails and all sorts of pests that creep and crawl.
As its name implies, it is made of diatoms, specifically thei very old, very dead and very fossilized remains. These diatoms were once algae swimming in the sea, except they are special due to their hard shells which are composed of silica.
Eventually these fossilized diatoms get compacted into a type of sedimentary rock where it is crushed up for many human uses such as filterization (the diatom shells are very porous), cat litter, dynamite and as a mechanical insecticide (<-- what wiki says, very interestingly to put it. Wish there were some gears and cogs included like it sounds).
OK, so to get actually scientific rather than bellicose sounding about how diatomaceous earth works (I feel so Alton Brown-ish, which is funny to say because I don't watch tv), apparently while it is abrasive in nature and can potentially cut-up slugs/snails so that they lie bleeding in my beds to be composted, the powder of D.E. is so fine that it absorb the outer shell lipids of your pest, anthropod and cockroaches all lumped together. By absorbing the lipids, like a person using baby powder (or you know how those silica packets in food say "DO NOT EAT" because they'll suck you dry from the inside out), well the pest will lost a dramatic amount of water and die due to loss of water pressure.
That was more gruesome than I thought. Ick. Mm! Mm! Dessicated slugs. (I feel a little bad now).
Interesting still yet, diatomaceous earth (medical grade) can be used to de-worm animals (even humans) and is often used in grain storage to prevent pests from decimating the supply.
When applying the D.E. I used a wire colander and would tap under and over and in-between the plants I wanted to protect. (STRAWBERRIES. Last year, the sluggies got a LOT of them. There will be no victory for them this year!) It's smart to use a face mask (I don't. Woo, white lung. No, I just don't breathe much when doing this. I know, smart) and wear gloves as the powder is quite drying (I don't either and just wash and moisturize afterwards). I just make sure that the powder is liberally laden on the lower parts of the plants stems and ground so crawlies will get into it.
If you don't want to use a colander you can use a vintage flour sifter which are always cheap to devote to powdering your plants. Many ways to go about this of course.
Like most pesticides, reapplication is necessary after it rains and to be honest, it is suspect as to the efficacy of the powder in humid environments like where the slugs reside. I don't think I see as much damage as I usually do on my plants, but the strawberries are just beginning to turn red, and once they are fully ripened the slugs see that as "go time!" to nosh down, so currently this is just my pre-emptive strike agains slug-fest 2010.
(I have used the beer-swamp of death method in the past to stop slugs and still hand pick, but for my amount of slugs and sanity this was easier. I also often relocate toads from the park/neighborhood to my garden. Is this illegal? O_O)
If you do want to use D.E. go for the largest bag you can find for cost savings because it's not the cheapest. A 5 pound bag was $13 at cheapest for me in my area, but I already have used it numerous times and there's a good amount left depending on how liberally you do apply and how often you need to (I only reapply after rain).
Best of luck with your bugs!