Of the roughly 4,500 cockroach species in the world, about 55 are found in the United States. None of the native ones are considered major pests. Instead, they generally avoid humans, preferring such habitats as sand, rotting wood and leaf litter. “For ecosystem functioning, they’re really important because they get rid of all this garbage in the world,” like decomposing plant and animal matter, said Jessica L. Ware, an assistant professor at Rutgers University-Newark who co-authored the recent paper. “They’re not specialized to dwell in the kitchen and to scavenge for scraps.”
Although these native cockroaches stay largely out of sight and out of mind, their exotic cousins are a different matter. American cockroaches, which, their name notwithstanding, originated in tropical Africa, are believed to have come to the United States during the early days of the slave trade. Later arrivals include the oriental cockroach, the German cockroach, the Turkestan cockroach, the Australian cockroach, the brown-banded cockroach and a few others, all of which take up residence in people’s homes. Many of these names are equally as misleading as the American cockroach, illustrating more about the societal prejudices of the time than anything else. “German roaches are not called German roaches in Germany,” Lou Sorkin, an entomologist at the American Museum of Natural History, pointed out. “They’re called Polish roaches.”
The Japanese cockroach, or Periplaneta japonica, is the latest to appear in America. Native to central and northern Japan, humans first accidentally spread them to similar latitudes in continental Asia. Then, in spring 2012, an exterminator working on the High Line, a popular park that winds along an abandoned elevated railway in Manhattan, noticed some unusual-looking cockroaches in rodent bait stations. “Exterminators, they know their roaches,” Ware said. “He knew it wasn’t one of the standard players.” As a result, he sent some specimens to a scientist at the University of Florida, who in turn contacted the Smithsonian. Ware, who has published several cockroach papers, was subsequently brought in. Using DNA extracted from the middle legs of a male and a female, she and Ph.D. candidate Dominic Evangelista confirmed that they were indeed Japanese cockroaches—the first record of this species in the United States.
Ware and Evangelista speculate that these Japanese cockroaches hitched a ride to the High Line in the soil of ornamental plants that now line the park. Unlike most of their relatives, they produce a type of antifreeze that allows them to survive in cold temperatures, and they have even been found on ice. They therefore may be able to overwinter outdoors in New York, giving them a potential competitive advantage over other cockroaches. Ware said that although Japanese cockroaches thrive in urban environments and could perhaps spread rapidly, there is likely little cause for alarm. In fact, the increased competition could even cause the total number of cockroaches to drop. “The one that is the most abundant pest has changed over time,” she explained, adding that each species gets its “15 minutes of fame.”
This upcoming summer, Ware hopes to get a population estimate for Japanese cockroaches along the High Line. A self-proclaimed cockroach lover, she said she enjoys picking them up and handling them in the field. But even she draws the line at home. “I don’t want to get giardia,” she said in reference to one of the diseases, a stomach bug, that cockroaches are capable of transmitting. “And I don’t want them crawling on my food.”