I use this dust in a hand cranked duster. I usually have a breeze so I get on the side of the garden to let the breeze carry the dust across the garden. The dust appears to kill most garden insects. It takes very little time for it act. I usually wait about 30 minutes and spray the garden plants down to get rid of the dust. I try to dust when the bees are not active. I wash it off so the residual dust doesn't continue to kill. I find that I can keep my garden pest to a low level and kill the least amount of good bug.
I tried using cans of top name sprays to kill yellow jackets under a wood step in my garden, the ones entering and exiting would die but in two days there were more, as if I had done nothing. I used Bayer Advanced Complete Insect Dust and the next day they were gone and stayed gone. I had concerns that the rain that evening would wash the dust away, but it didn't, I turned into a kind of paste which had to be wiped off. I recommend it for this use.
I sprinkle a small amount around my house where the wall and slab meet. The next day there are dead insects everywhere. Pill bugs, beetles, scorpions,fleas, everything that was headed into/around the house. Very good and easy to use.