The Japanese hornet, Vespa mandarinia, is a large insect that often captures public attention due to its imposing appearance. Understanding its specific visual characteristics is important for accurate identification. This article describes its distinct features, dimensions, and how it visually differs from other insects it might be mistaken for.
Key Physical Features
The Japanese hornet possesses a distinctive coloration. Its broad head is typically a prominent yellow-orange hue, contrasting sharply with its dark brown to black thorax. This two-toned body structure is a consistent visual marker for the species.
Its antennae are generally a medium or dark shade of brown, with yellow-orange scapes, which are the basal segments. The hornet features large compound eyes, from dark brown to black, complemented by three simple eyes (ocelli) between them. A prominent, deeply incised clypeus (the plate above the mandibles) and large genae (cheeks) contribute to its notably wide head.
The mandibles are substantial and a deep orange, equipped with a black tooth. The abdomen displays an alternating pattern of dark brown or black bands and yellow-orange stripes, creating a bold, banded appearance. Its wings are often smoky brown with dark veins.
Size and Scale
The Japanese hornet is recognized as the largest hornet globally. Queen Japanese hornets can exceed 5 centimeters (2 inches) in body length, with wingspans potentially reaching over 7.6 centimeters (3 inches). A queen is comparable in length to a human thumb or a standard AA battery.
Worker hornets are somewhat smaller, typically measuring between 3.5 to 4 centimeters (1.38 to 1.57 inches) in body length. Despite the difference in length, workers and queens share the same coloration. Their wingspan can extend up to 7.5 centimeters.
Distinguishing from Similar Insects
Distinguishing the Japanese hornet from other large insects is important. The European hornet (Vespa crabro) is generally smaller, with queens growing up to 3.5 centimeters, and often exhibits more reddish-brown tones with tear-drop shaped markings on its abdomen. In contrast, the Japanese hornet’s head is distinctly orange or yellow-orange, and its abdominal stripes are more uniformly banded without tear-drop shapes. European hornets also typically have brownish legs, while Japanese hornets have dark legs that transition to yellow at the ends.
Cicada killers (Sphecius speciosus) are another group of large wasps sometimes confused with Japanese hornets due to their size. Cicada killers generally have uneven yellow stripes on their abdomen that peak in jagged patterns, whereas the Japanese hornet has smoother, more evenly distributed yellow-orange or brown bands. The head of a Japanese hornet is notably wide and orange, often as wide or wider than its shoulders, and contrasts in color with its dark thorax. Conversely, cicada killers have narrower heads that are typically the same dark brown color as their thorax.