The Japanese Hornet, formally known as Vespa simillima xanthoptera, is a species of social wasp native to East Asia, primarily inhabiting Japan and parts of the Korean Peninsula. The nesting habits of this adaptable species differ from many of its relatives, showing a preference for concealed, protected cavities across various environments.
Identifying the Japanese Hornet and its Range
The Japanese Hornet is a subspecies of the Yellow Hornet, distinguished by prominent yellow markings on the abdomen. Workers measure between 17 and 23 millimeters in length, while queens reach up to 28 millimeters. This medium-sized species is often confused with the much larger Asian Giant Hornet, Vespa mandarinia, which can exceed 45 millimeters.
The native distribution spans the main islands of Japan, the Korean Peninsula, eastern China, and parts of the Russian Far East. The xanthoptera form is most prevalent in central and southwestern Japan. This hornet demonstrates high adaptability, thriving in densely wooded areas as well as in human-modified urban and suburban landscapes.
Habitat Selection: Primary Nesting Sites
The Japanese Hornet utilizes a wide variety of locations, showing flexibility between subterranean and aerial sites, unlike the Asian Giant Hornet, which almost exclusively nests underground. In natural habitats, the hornet prefers existing protective cavities. These sites include hollowed-out tree stumps, large cavities within dead wood, or protected spaces underneath complex tree root systems. Colonies may also be founded in small, pre-existing voids in the ground, such as abandoned rodent burrows.
The entrance to these subterranean nests is often a small, inconspicuous hole, making them difficult to locate. The xanthoptera subspecies is also known for its adaptation to urban environments, where structural voids become primary nesting locations. Frequently used aerial locations include attics, wall voids of buildings, overhangs of roofs, and sheltered spaces beneath eaves. This tendency contributes to the species being a nuisance pest in residential areas.
Nests built in these enclosed spaces are typically oval-shaped and feature an imbricate outer envelope. This envelope consists of numerous overlapping layers made from chewed wood fiber, providing a robust, protected environment for the developing colony.
The Annual Life Cycle of the Colony
The nesting cycle of the Japanese Hornet is annual, beginning with a solitary queen emerging from hibernation in the spring. The founding queen selects a new nesting site, begins construction, and lays the first batch of eggs. She cares for the initial brood until the first generation of sterile worker hornets emerges in the early summer.
The colony grows rapidly throughout the summer as workers take over foraging and nest expansion duties. The southern subspecies, xanthoptera, is believed to achieve large colony populations due to a longer nesting period.
By late summer and early autumn, the colony shifts focus to producing new males and virgin queens. These new queens mate before dispersing to find sheltered spots for hibernation, marking the end of the colony. The founding queen, workers, and males die as temperatures drop, and the nest is completely abandoned, as the Japanese Hornet never reuses a nest from a previous year.