Nicotine poison works on tobaccos enemies by addiction. When the enemy takes the nicotine a strong desire for more occurs. This ends for most of tobaccos predators in a spiral of death from over indulgence. The insect humans however have proven most difficult to kill off with the poison; it takes a lot longer for the nicotine to cause their deaths, but they are woking to improve their lot. I use tobacco spray for scarid fly infestations on my plants. Boy do they get burned!