Something new to creep you out: Researchers from Rutgers University have found that bed bugs that were allowed to feed after being treated with insecticides had greater rates of survival or they took longer to die than those not allowed to feed after being treated.

The findings, published in the Journal of Medical Entomology, may explain why certain pesticides are ineffective in treating bed bugs, which are posing a growing threat in hotel rooms and dwellings in many major metropolitan areas.

Specifically, the researchers found that bed bugs that were unable to feed after being sprayed with an insecticide had a mortality rate of 94 percent. But those that did feed after being sprayed with the same insecticide had a mortality rate of just 4 percent after 11 days.

"Many of the insecticides labeled for bed bug control may not be as effective as claimed, because of the inadequate testing method," said Dr. Narinderpal Singh, one of the co-authors. "People often use laboratory bioassay results to predict field performance of an insecticide.

“It is important the testing conditions are similar to what would occur in the field. Current established test protocols for bed bug insecticides do not provide bloodmeals to bed bugs during the test period. We suspect the mortality data typically observed might be different if the tested bed bugs were provided a bloodmeal during the observation period."

The researchers suggest that feeding "stimulates detoxification enzymes responsible for insecticide resistance," and that non-pesticide alternatives — including barrier methods and heat treatments — may be the best way to target  bed bugs.

"Incorporating non-chemical methods into bed bug control is very important in order to achieve good results," said Dr. Singh. "Some examples of non-chemical methods include vacuuming visible bed bugs, applying steam to furniture and baseboards, laundering bed sheets and infested clothing, encasing mattresses and box springs with bed bug encasements, and installing interceptors under the legs of beds and upholstered furniture."