The first and second generation insecticides act on
systems important for survival in both pest and other
organisms including mammals. They therefore lack
the selectivity which is theoretically possible with
hormones or antihormones, agents that disrupt cuticle
or chitin formation, or other types of insect
growth regulators. These "third generation" insecticides
have not yet been perfected for extensive use,
and there are definite limitations in the types of pest infestations where such slow-acting compounds are
likely to prove acceptable. Chemical control of insects
depends almost completely at present on first
and second generation insecticides including pyrethrins
and pyrethroids. The common names of important
compounds are given in Table 1.