Last updatedLast updated: July 12, 2022
Pest Products is reader-supported. We may earn a commission through products purchased using links on this page. Learn more about our process here

Insect Growth Regulators

Growth inhibitors or insect growth regulators (any of which is commonly known as an IGR) are products or materials that interrupt or inhibit the life cycle of a pest.  Many people loosely use the terms “birth control for roaches” or “birth control for fleas.”  If an animal cannot reach adulthood, it is not capable of reproducing.  By inhibiting the maturity of an insect, we keep it from reaching the critical adult stage, thus stopping the life cycle and infestation.   In layman’s terminology, an IGR is not an insecticide (in the bug killing definition) but is a man-made protein that only effects certain insects or groups of insects.
Flea eggs and flea larvae that are exposed to an IGR (NyGuardNylarPrecorMethoprene) will never develop into the adult jumping, biting and (most important!) reproducing fleas.  As another example, roaches that are exposed to either Nyguard IGRNylar or Hydroprene cannot shed their exoskeleton or develop a new exoskeleton.  This is an important part of the roach life cycle: if they cannot shed their outer shell or grow a new one, they cannot mature any further.
The following materials (active ingredients) are the most widely used insect growth inhibitors by pest professionals, pest control operators (PCO) and individuals doing their own pest control: PyriproxifenMethopreneHydropreneNylar.


When used indoors, Methoprene (the active ingredient in PrecorPrecor 2000 and others) will prevent the egg and larvae stages of fleas from developing, with a 3 to 7 month residual.  Use alone for prevention or tank mix with an approved insecticide (Suspend SCPermethrin Pro) for existing problems.  Precor also works on Cigarette Beetles.  Methoprene (or Precor) is not photostable and is for indoor use, only.  Available in liquid concentrate and aerosol formulations for indoor flea control.  Methoprene can also be found in Frontline Plus topical flea and tick treatments for dogs and cats.  Methoprene is combined with Fipronil in Frontline Plus products.  Fipronil kills and repels ticks and adult fleas as the Methoprene inhibits the growth of immature fleas.

Flea Elimination   Cigarette Beetle Elimination


The IGR Nylar is the active ingredient inNyGuard, ArcherFlea Fix and others.  This material is photostable (can be used outdoors and indoors) and inhibits the growth of fleas and roaches.  Nylar has a 3 to 6 month residual indoors and can last 30 days when used outdoors.  This IGR can be used alone (for roach and flea prevention) or tank mixed with an approved adulticide.  Cypermethrin insecticides or Orthene work best for roaches; Suspend SC or Permethrin Pro work best for fleas.  Available in liquid concentrate and aerosol formulations.

Order NyGuard  Order 1 ounce Nylar    Order 4 ounce Nylar    Order 16 ounce Nylar

Roach Elimination   Flea Elimination


This IGR is the active ingredient used in GentrolGentrol Point SourceGentrol Aerosol.  Hydroprene is not photostable and is for indoor use, only.  Use this IGR when eliminating, controlling or preventing cockroaches (roaches) and many pantry pests.  Cigarette Beetles are not affected by Hydroprene; use Methoprene instead.  Can be tank mixed with adulticides (insecticides) or used alone.  Available in liquid concentrateaerosol and in solid dispensers.

Leave a Reply

Your email address will not be published.