This product has been so helpful to deal with the ongoing problem of swarms of pesky fungus gnats! Fungus gnats kept trying to fly up everyone's nose in our house! Gnats had infested all our houseplants when some plants were brought in the house for the winter. I had tried numerous alternate recommendations, but repeated attempts only temporarily reduced the population. During application I took the precaution of wearing a mask because I understand it is recommended that you do not breath in diatomaceous earth. I like that it stays in the soil and prevents further re-infestation if any gnat larvae happen to re-infest the soil. I believe it does not harm earthworms. Since this particular brand is labeled as food grade, I felt comfortable applying it to the soil of edible plants such as herbs, and I feel it was a good alternative to using chemical pesticides. Only a small amount was needed per plant so I have lots of it left over if I need it again next season.