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Friday, Sept. 13, 2002

ANIMAL TRACKER

Giant hornet


* Japanese name: Oo-suzumebachi
* Scientific name: Vespa mandarinia japonica
* Description: This monster is the largest social wasp in the world. Workers grow to between 25 and 35 mm long, drones (males) up to 45 mm long, and queens a startling 55 mm in length. Giant hornets have wide, orange heads and large, powerful mandibles (jaws). The wings are smoky-brown, the thorax is black and the abdomen is unmistakable: black-and-orange stripes. The compound eyes and the ocelli (the three simple eyes on the top of the insect's head) are dark brown.
* Where to find them: In mountainous and wooded areas all over Japan, from April to October. Giant hornets build nests from wood, which they chew up and mix with saliva to make pulp. But if you see a hornet's nest, beware of approaching it.
* Food: Other insects, especially other wasps and bees. When a solitary hornet discovers a bees nest, she marks it with a secretion. This attracts other hornets to the nest, and they launch a massive attack on the bees, crushing them in their jaws at a rate of up to 40 per minute each. When the bees have been wiped out, the hornets feed on the helpless bee larvae inside. This attack devastates nests of European honey bees (introduced relatively recently to Japan), but Japanese honey bees have evolved a countermeasure. Facing a hornet attack, around 500 bees surround the hornet and form a tight, vibrating ball. The temperature inside the ball quickly rises to 47 degrees, which kills the hornet. (Bees can tolerate slightly higher temperatures, so they don't die.)
* Special features: Giant hornets can fly at up to 40 kph and can cover 100 km in a day. They have a sting that can be dangerous to humans. The stinger is a modified ovipositor (egg-layer) that is connected to a venom sac inside the body. Unlike bees, wasps can withdraw the stinger and puncture the skin again, repeatedly injecting venom. Queens use their ovipositor to lay eggs, so they can't sting. Neither can males, because they don't have an ovipositor in the first place. The workers, however, are sterile females, and they are the ones to watch out for.



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