Pyrethrin/permethrin are the synthesized and natural chemicals from a flower from Africa. It is totally safe around mammals, however, it can kill fish,amphibians,reptiles and birds. What you really need to understand is the label. A quick look at many insecticides will list a small percentile of the listed chemical. Notice the 98% material listed as inert material. What you are spraying on you is usually a petroleum based compound to act as a carry medium. And what the industry also will not reveal, are the additional "boosters" added to that inert base. Permethrins will only last a few hours at best, and are most effective in a water based medium. I prefer some rather old fashioned remedies; smudging with local plant materials, using as smoky fire when at base and lastly what elephants do- cover my exposed features in mud <img src="images/graemlins/blush.gif" alt="" />