It's great for killing fleas. Treated my yard 4 years ago when we bought the place 4 years ago and haven't seen a flea on the dog since!! And man, was this yard ever infested with them when we purchased. They were even biting ME every time I walked in the back yard. Nary a one since, truly. I've not had to re-treat.
Kill the big outdoor cockroaches, too. They're not bad in our neighborhood, but almost every single day I will find one of the outdoor type on my hardwood floors "belly up", still wiggling his legs, yet nobody swatted it. Don't know how they get inside, but I don't have to lift a finger to kill them, other than pick them up with a tissue and throw them in the trashcan. Guess bits of the DE are still on the soil and roaches lick their legs in a post-eating/groom process. Of course, they may be walking through my neighbor's yard first. They spend a small fortune treating their yard once a month with chemicals (though not sure what bug for), even though I told her how effective DE was on bugs some 4 years ago. Each to their own.
Basically, DE kills any insect with an exoskeleton, as the sharp bits of crustacean shell cuts the exoskeleton. Quickly then the bug dehydrates and dies. As long as flying bugs with exoskeletons stay in the air and high up on plants and flowers (like bees) they won't be bothered. But if they walk down on the soil where the DE lies,.......well, it would likely kill them as well. DE doesn't discriminate. It will scratch/cut all exoskeletons. But luckily I have not had to re-treat in 4 years, fleas are gone, and I assume most of the DE is washed down into the soil so that it is likely to not be a problem for bees anymore, if it ever was.
