Wintertime Warriors: Cockroaches and Bed Bugs Found to Tolerate Cold Weather

Just in time for winter, two new studies in the Journal of Economic Entomology detail an Asian cockroach with a knack for surviving outside in cold weather and bed bugs that may be less susceptible to freezing temperatures than previously believed.

Periplaneta japonica, the winter-ready Asian cockroach, has been confirmed for the first time in the US in a place that already knows cockroaches all too well: New York City. It was first discovered in 2012 by an exterminator working in the city's High Line park, which is adorned with a variety of native and non-native plants. It is likely that the roach came into the city as a stowaway in the soils of the imported ornamental plants that were installed in the park.

"Many nurseries in the United States have some native plants and some imported plants," said Rutgers University insect biologists Jessica Ware, "so it's not a far stretch to picture that that is the source."

Ware and her colleague Dominic Evangelista were enlisted to investigate the presence of the cockroach after a New York exterminator noticed how the roach was different than ones typically found in the city.

Now, researchers will need to monitor the japonica roach to determine whether it will pose a threat to native roaches.

"To be truly invasive, a species has to move in and take over and out-compete a native species," Michael Scharf, a professor of urban entomology at Purdue University, told The Associated Press. "There's no evidence of that, but that doesn't mean we shouldn't be concerned about it."

Though many New Yorkers may not think the arrival of a new cockroach species sounds like good news, the added competition the Asian roaches bring to city roaches may end up lowering overall roach numbers.

"Because this species is very similar to cockroach species that already exist in the urban environment, they likely will compete with each other for space and for food," Evangelista said.

Ware added: "Their combined numbers inside buildings could actually fall because more time and energy spent competing means less time and energy to devote to reproduction."

In a separate study also published in the Journal of Economic Entomology, researchers detail how bed bugs defend against freezing temperatures by lowering the freezing point of their body fluids. Placing a bed bug-contaminated item in the freezer is a common home remedy to kill the pests, but the new study indicates that in order to sufficiently kill the critters, they'll need to be frozen for quite some time.

Researchers from the Entomological Society of America found that in order to achieve 100 percent mortality, a minimum exposure of 80 hours at minus 16 Celsius (3.2 degrees F) is needed. At temperatures of minus 20 C (minus 4 F), 100 percent mortality can be achieved in 48 hours.

However, even if the temperature is as cold as minus 25 Celsius (minus 13 F), bed bugs eggs were documented surviving for short periods of time.

The researchers recommend homeowners trying to decontaminate an item infested by bed bugs to place the item in a plastic bag in the freezer for four days.