Asian giant hornet
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The Asian giant hornet (Vespa mandarinia), the world's largest hornet, is a native to the mountains of Japan. Its body length is between 27 mm (1.1 inches) and 45 mm (1.8 inches), with a wingspan of about 76 mm (3 inches). Queens may reach a length of 55 mm (2.2 inches).
Anatomy
The head of the hornet is orange, and quite wide in comparison to other hornet species. The compound eyes and ocelli are dark brown and the antennae are dark brown with orange scapes. The clypeus (the shieldlike plate on the front of the head) is orange and coarsely punctured; the posterior side of the clypeus has narrow rounded lobes. The mandible is large and orange with a black tooth (inner biting surface).
The thorax and propodeum (the segment which forms the posterior part of the thorax) of the Asian giant hornet has a distinctive golden tint and a large scutellum (a shieldlike scale on the thorax) that has a deeply-impressed medial line; the postscutellum (the plate behind the scutellum) bulges and overhangs the propodeum. The hornet's forelegs are orange with dark brown tarsi (the distal - furthest down - part of the leg), the midlegs and hindlegs are dark brown. Wings are a dark brownish-gray. The tegulae are brown.
The gaster (the portion of the abdomen behind the thorax-abdomen connection) is dark brown with a white, powdery covering; with narrow yellow bands at the posterior margins of the tergite, the sixth segment is entirely yellow.
Geographic Distribution
Mostly the mountains of Japan, but may be found in most of Asia: southeastern regions of Asian Russia (Primorskii Krai), Korea, China, Japan, Indochina, Nepal, India , Sri Lanka, Thailand.
"Hornets From Hell"
Sting
The stinger of the Asian giant hornet is about a quarter-inch (6.35 mm) in length, and injects an especially potent venom that contains an enzyme so strong that it can dissolve human tissue. Masato Ono, an entomologist at Tamagawa University near Tokyo, described the sensation as feeling "like a hot nail through my leg." [1]
If a person is stung by the giant hornet and doesn't receive prompt medical treatment, he or she may die from a reaction to the venom. About 40 people die each year after being stung by giant hornets, mainly as a result of an allergic reaction to the venom.
A couple of interesting notes on the V. mandarinia's venom and stinger:
- The venom contains 5% acetylcholine which stimulates the pain nerve fibres more than bee or other wasp venoms so that it is a bit more painful.
- The venom is optimized to kill bees which are the V. mandarinia's natural prey. This means that while the venom may be a bit more painful to vertebrates, it is actually less toxic.
- Like all hornets, V. mandarinia can sting repeatedly, and do so when they prey on bees and other insects.
Predation
The Asian giant hornet is a relentless hunter that preys on other large insects such as bees, other hornet species, and praying mantises.
The hornets often attack honeybee hives with the goal of obtaining the honeybee larvae. The hornets can devastate a colony of honeybees: a single hornet can kill as many as 40 honeybees per minute; it takes only a few of these hornets a few hours to exterminate the population of a 30,000-member honeybee hive, leaving a trail of severed insect heads and limbs. Once a hive is emptied of all defending bees, the hornets carry the honeybee larvae back to feed to their own larvae.
Rather than consume their kills directly, the hornets chew them into a paste and feed them to their larvae. The hornet larvae, in return, produce a clear liquid which the adults consume (see The Hornet and the Japanese Diet, below).
Native Honeybees
Although a handful of Asian giant hornets can easily defeat the defenses of honeybees, whose correspondingly small sting cannot inflict much damage against such a large predator as the giant hornet, the Japanese honeybee (Apis cerana japonica) has evolved an ingenious method of defending against the much larger predator.
When a hornet scout locates a Japanese honeybee hive and approaches the nest, the scout will emit specific pheremonal hunting signals. When the the honeybees detect these pheremones, a hundred or so honeybees will gather near the entrance of the nest, apparently to draw the hornet further into the hive. As the hornet enters the nest a large mob of about five hundred honeybees surround the hornet, completely covering it and preventing it from moving, and begin quickly vibrating their flight muscles. This has the effect of raising the temperature of the honeybee mass to 47 °C (116.6 °F). Though the honeybees can tolerate such a temperature, it is fatal to the intruder, which can handle a maximum temperature of about 45 °C/113 °F, and is effectively baked to death by the large mass of vibrating bees. [2]
The Hornet and the Japanese Diet
In Japan's mountain villages, the hornets are valued as part of the basic diet. They are eaten deep fried, or as a kind of hornet sashimi.
More recently however, several companies in Asia and Europe have begun to manufacture dietary supplements and energy drinkss containing the secretions of the larvae of Vespa Mandarina Japonica, which the adult hornets usually consume. According to the manufacturers of these products, because the adult hornet can fly 50 miles in a single day at 20 miles per hour, consuming the larval hornet secretions (marketed as "hornet juice") will similarly enhance human endurance.