The Japanese cockroach (Periplaneta japonica), also known as the Yamato cockroach,[1] is a cockroach native to Japan, adapted to cooler northern climates.[2][3][4] It has a flexible univoltine or semivoltine (one- or two-year) lifecycle, depending on the timing of its hatching, and is unusual in being able to spend two winters as diapause nymphs before reaching maturity.[3]

Freeze tolerance [ edit ]

Nymphs have been observed in the wild hibernating in subfreezing temperatures during winter in snow-covered habitats.[5] Overwintering nymphs were able to survive laboratory supercooling experiments in the -5 to -8 °C temperature range, enduring 12 hours of tissue freezing,[6] as well as recover from burial in ice.[1] The ability to walk on ice was also found to be unique among several cockroach species tested.[1]

Physiology [ edit ]

Initial first-instar nymphs are dark brown, with white or brownish white tips of the maxillary and labial palps. Adults measure 25–35 mm in length, and have a shiny, uniformly black to blackish-brown body, with brown tarsi and maxillary and labial palps. The adult male's wings extend slightly beyond the body's length, while the female's wings are around half the body's length.[7]

Unlike most cockroaches, the major hydrocarbon in P. japonica’s cuticular lipids is cis-9-nonacosene.[8] Males have significant amounts of cis-9-heptacosene not found on females.[8] Glucose, myo-inositol, scyllo-inositol and trehalose were found in overwintering nymphs and are thought to be a factor in their freeze tolerance.[6]

Habitat [ edit ]

Primarily an outdoors species, populations are adaptable to living indoors in houses and buildings where food is stored, prepared, or served.[7][9]

Defense [ edit ]

A P. japonica nymph alone or in sparse populations accumulates a viscous secretion along its rear dorsal surface, droplets of which it can be splashed some distance toward a threat through a shaking action. The presence of an aggressive species of ant, Formica exsecta, triggered this defensive response, rendering the ants helpless.[10]

Invasive species [ edit ]

Originally from Japan, P. japonica has spread to China, Korea and southeast Russia, though it is considered a common pest primarily in central and northern Japan.[4][7][9][11]

The species was found in New York City in 2013, the first time the species was found in the United States.[12] It was found by an exterminator beneath plantings in High Line, a Manhattan park, and was able to survive over a cold winter.[13] Scientists who confirmed the identity of the species through genetic testing theorize that it may have been imported in the soil of ornamental plants used in the park.[12]