While Maine’s cool temperate climate may not be hospitable to a large number of insect pests, the most pestiferous cockroach pest species get along just fine in the Pine Tree state. The cockroach species that frequently establish infestations within homes and buildings in Maine include German, American, Oriental and brown-banded cockroach pest species, though German cockroaches are, by far, the most commonly controlled roach pests in the state. All four of these species are capable of reproducing within homes, and although American and Oriental cockroach species are two extremely problematic pests, they generally prefer outdoor conditions. However, this is not the case for both German and brown-banded cockroaches, as these two species have evolved to dwell solely indoors.

While brown-banded cockroach populations throughout the US have dwindled significantly in recent years, German cockroaches will never disappear from human settings. Due to decades of pesticide overuse within homes, German cockroaches have become physiologically resistant to virtually all pesticide formulations, making the introduction of new pesticides for cockroach control pointless. Despite this, a new class of residual pesticides were used up until recently with the hope that they would be more effective for cockroach control. Of course, they were not, but this is not necessarily because German cockroaches developed a resistance to residual pesticides.

Residual pesticides are sprayed onto certain indoor surfaces and cracks and crevices where cockroaches are expected to make contact. Although residual pesticides proved effective in laboratory conditions, they failed to eliminate indoor infestations. This is due to the fact that, after mating, female cockroaches remain stationary within concealed indoor spaces for weeks in order to gestate, and by the time they emerge, residual pesticides have long since worn off of surfaces. Nymphs also tend to remain stationary within indoor hiding spots during their development, which can take a longer time than laboratory observations would suggest, as nymphs develop more slowly in their natural habitat where food is more difficult to attain. Nymphs account for the greatest number of specimens within infested homes, which makes their extermination essential for the elimination of infestations. However, rather than emerging to forage, nymphs consume the fecal matter of their mother’s feces for sustenance. While nymphs and females remain hidden, residual pesticides degrade, allowing females and nymphs to survive while males succumb to the treatment. After discovering this shortcoming, residual pesticides were abandoned in favor of baits containing slow-acting poison that spreads through roach colonies via grooming and mutual feces consumption.

Have you ever used over-the-counter bait to control a roach problem in your home?