If you read the back of the container it usually has a ratio of how much of the pesticide kills how many of the target insect. That's usually pretty effective in establishing the toxicity of a given chemical. I've never had any bad experience with bees and fogger despite in the summer, if you want to be outside around dusk you MUST use it. Lately it's been getting overuse with the whole scare of West Nile Virus and the dying pigons.