What life stage does an insect growth regulator (IGR) prevent fleas from reaching?

Insect growth regulators (IGRs) are chemicals that disrupt the normal development of insects, affecting their growth and maturation. When it comes to fleas, IGRs specifically target the developmental stages after the egg stage, meaning they interfere with the progression into the adult stage.

Fleas undergo several life stages: egg, larva, pupa, and adult. The primary function of IGRs is to prevent larvae from developing into adults, which is crucial because adult fleas are the ones that bite and feed on their hosts. By preventing the larvae from maturing into adults, IGRs effectively reduce the overall flea population and break the cycle of infestation.

This mechanism of action is why IGRs are widely used in flea control products. They can significantly lower the chances of fleas reproducing and establishing a larger infestation while allowing the other life stages (such as eggs and larvae) to exist without immediate health impacts on pets or humans.