These are products or materials that interrupt (break) or inhibit the life cycle of a immature pests. These products are often used with liquid sprays for restaurants (cockroaches) or for (flea) infestations in homes.

This isn’t the best picture but notice the German roach with curled wings, this is an indication that this roach came in contact with an IGR. Some IGR’s make the insect a darker color while others stop them from molting (shedding their exoskeleton) or reproducing.