Japanese cockroach
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Blattodea
Family:	Blattidae
Genus:	Periplaneta
Species:	P. japonica
Binomial name
Periplaneta japonica Karny, 1908

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]

Initial first-instar nymphs are dark brown, with white or brownish white tips of the maxillary and labial palps. Adults measure 25–35 millimetres (2+1⁄2–3+1⁄2 cm) 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.^[5]

Unlike most cockroaches, the major hydrocarbon in P. japonica’s cuticular lipids is cis-9-nonacosene.^[6] Males have significant amounts of cis-9-heptacosene not found on females, as do P. australasiae and P. fuliginosa males and females.^[6] Glucose, myo-inositol, scyllo-inositol and trehalose were found in overwintering nymphs and are thought to be a factor in their freeze tolerance.^[7]

Nymphs have been observed in the wild hibernating in subfreezing temperatures during winter in snow-covered habitats.^[8] Overwintering nymphs were able to survive laboratory supercooling experiments in the −5 to −8 °C (23 to 18 °F) temperature range, enduring 12 hours of tissue freezing,^[7] 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]

Primarily an outdoors species, populations are adaptable to living indoors in houses and buildings where food is stored, prepared, or served.^[5][9]

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]

Originally from Japan, P. japonica has spread to China, Korea and far eastern Russia, though it is considered a common pest primarily in central and northern Japan.^{[4][5][9][11]}

The species was found in New York City in 2013 by Evangelista et al.,^{[12]: 581 [13]: 40 [14]} the first time the species was found in the United States.^[15] It was found by an exterminator beneath plantings in High Line, a Manhattan park, and was able to survive over a cold winter.^[16] 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.^[15] This identification demonstrates the use of DNA barcoding for urban pest control.^[12][13]