The Japanese hornet, Vespa mandarinia, is the largest hornet species globally; queens can reach nearly two inches in length. Its size and potent venom have given it a reputation, especially due to its predatory nature toward honey bee colonies. This social insect belongs to the wasp family Vespidae and has a large orange-yellow head and a black and yellow-orange striped abdomen. Understanding its geographical distribution is important for managing its presence and predicting its potential spread.
The Native Range in Asia
The established, historical distribution of Vespa mandarinia is confined to a vast area across Asia, covering both continental and island regions. This range extends throughout East Asia, South Asia, and parts of Southeast Asia, generally inhabiting regions north of the tropics. It is most abundant in Japan, which gives rise to its common name, the Japanese hornet.
The hornet’s distribution includes countries such as China, Taiwan, and the Korean Peninsula, stretching westward into the Russian Far East. Further south, it is naturally found in regions like India, Nepal, Bhutan, and Myanmar, with confirmed occurrences also noted in Thailand and Laos. This wide geographical spread means the hornet is adapted to a variety of climates, ranging from temperate zones in the north to more subtropical conditions further south.
The species is most commonly found in low mountains and forested areas, favoring environments that are not highly urbanized. While it can thrive across this broad area, populations are generally more concentrated between the temperate and tropical zones. It is notably absent from high-altitude areas and large plains, suggesting a preference for specific geographical features that provide suitable nesting and foraging grounds.
Preferred Habitat and Nest Construction
Within its native range, the Japanese hornet selects specific environments ideal for its life cycle and predatory behavior. They primarily choose low-altitude forested areas, rural woodlands, and mountainous regions. These environments offer the necessary blend of prey availability and suitable dark, protected spaces for colony establishment.
The species is a forest dweller; its presence in urban landscapes correlates with the availability of green space, such as large parks or wooded lots. Foraging and hunting activities are concentrated in these wooded areas, where the hornets prey on various insects, including large beetles and other wasps and bees, to feed their developing larvae.
A characteristic of this hornet is its unique nesting habit, with colonies almost exclusively built in subterranean cavities. Queens typically select pre-existing underground spaces, such as abandoned rodent burrows, chambers near rotten pine roots, or hollows beneath tree root systems. The depth of these nests usually ranges between 6 and 60 centimeters below the soil surface, providing a secure, protected environment for the colony to grow.
These subterranean nests can grow quite large, sometimes containing up to 12 combs and thousands of cells for raising brood. While underground nesting is the overwhelming preference, occasional nests have been found in hollow logs or dead tree trunks above ground. Workers will enlarge the cavity and deposit soil pellets near the entrance, which serves as a visible sign of the nest’s location.
Global Monitoring of Invasive Populations
Outside of its native Asian range, Vespa mandarinia has become a subject of monitoring due to its potential as an invasive species. The most significant non-native detections occurred in the Pacific Northwest region of North America. Single hornets were first confirmed in late 2019 in Washington state and British Columbia, Canada, prompting concern and surveillance efforts.
Specific locations of concern included Whatcom County in Washington and areas like Nanaimo on Vancouver Island and Blaine near the border. These initial sightings and the subsequent discovery of nests indicated that the species had the potential to overwinter and establish a foothold in the region. However, there have been no confirmed sightings in any other U.S. state.
Entomologists and agricultural agencies have focused on an aggressive eradication and control strategy to prevent the establishment of permanent populations. Monitoring involves the deployment of specialized traps to capture individual hornets, which helps track their movements and locate the central colony. Once a nest is found, methods like carbon dioxide injection and subsequent removal are used to ensure complete destruction before new reproductive queens can disperse.
While the focus remains on Vespa mandarinia, a different but related species, Vespa velutina (the Asian hornet), has established populations in Europe, often leading to confusion in public reporting. Current evidence suggests that the V. mandarinia population in North America was successfully eradicated by late 2024, but monitoring continues to be a priority in climatically suitable areas. The control measures are designed to target the nests, as destroying the entire colony is the most effective way to eliminate the threat of spread.