Bio Kill penetrates the nerve membranes of cold blooded insects, causes nerves to paralyze and consequently the insects die. Humans and warm-blooded creatures have a different metabolism allowing the body to degrade the product without affecting the organism. Toxic onset can be anywhere between 2 to12 minutes, depending on the species, temperature, humidity etc. It is recommended to spray Bio Kill® as indicated on the label. Insects will die when contaminated with Bio Kill but often hide before dying.