The two types of biopesticides are biochemical and microbial. Biochemical pesticides may have a similar structure to, and function like, naturally occurring chemicals, and have nontoxic modes of action. Insect pheromones, for example, are naturally-occurring chemicals that insects use to locate mates. Man-made pheromones are used to disrupt insect mating by creating confusion during the search for mates, or can be used to attract male insects to traps. Pheromones are often used to detect or monitor insect populations, or in some cases, to control them.
Microbial insecticides are another kind of biopesticide.
They come from naturally-occurring or genetically altered bacteria, fungi, algae, viruses or protozoans. Bacillus thuringiensis is a naturally occurring soil bacteria that is toxic to the larvae of several species of insects but not toxic to nontarget organisms. Bacillus thuringiensis can be applied to plant foliage or incorporated into the genetic material of crops. Several strains of Bt have been developed and now strains are available that control fly larvae. These can be used in controlling mosquitoes and blackflies.