The incorporation of an insect growth regulator (IGR), such as NyGuard (pyriproxyfen), can be a very important part of a successful German cockroach (Blattella germanica) control strategy. IGRs prevent immature cockroaches from reaching their full “pest potential” by interfering with the nymphs’ molting process and reproductive development. Because IGRs do not directly kill the cockroaches, they are often coupled with an insecticide. The insecticide will kill some of the German cockroach adults and nymphs. The nymphs not killed by the insecticide will be affected by the IGR, either dying in the process of molting or rendered unable to reproduce due to induced deformations as adults.
Those who are not familiar with the effects of pyriproxyfen on German cockroach development may be concerned that a German cockroach infestation remains unaffected by treatment if immature cockroaches continue to be caught in post-treatment monitoring sticky-traps. Nymphal German cockroaches that have been exposed to pyriproxyfen will often exhibit specific developmental traits dependent on the insect’s life stage at the time of exposure. The pictures above show the effects of pyriproxyfen on nymphal German cockroaches, signifying that the IGR is, in fact, affecting the pest population.