*Japanese name: Taikouchi
*Scientific name: Laccotrephes japonensis
*Description: Also known as water scorpions and "toe-biters," these are ferocious, tough insects with strong, sharp front legs for catching prey (and biting toes or fingers) and a beaked hypodermic-type mouth with which they stab the body of their prey. They grow up to 30 mm long and their body and limbs are streamlined for efficient swimming. These bugs look a bit like beetles, but they lack the hard shell covering the wings that beetles have.
* Where to find them: In rivers and streams from Honshu to Kyushu. Around the stems of aquatic plants is the best place to find them, especially at the margins of river channels and in temporary pools. But be careful — their bite is notoriously painful, considered to be among the worst of all insect bites (excepting the stings of bees and wasps). Giant water bugs may also be found in flooded rice paddies, and they are capable of flying short distances to seek out new habitats.
* Food: Tadpoles are the most popular food items, and they stand no chance if they are trapped by a giant water bug's pincer legs. Larger bugs will also eat frogs, and smaller ones (and bugs at the nymphal stage) will take mosquito larvae and snails. But tadpoles are the favored prey, with the animal being held tight in the sharp legs and drained of blood by the syringe-like mouth. Unfortunately, they are also important predators of another, endangered, species of giant water bug. In some parts of Asia (for example, Thailand) this animal is itself eaten by humans, though I've not had the pleasure and I wonder if the practice has died out now in Japan.
* Special features: They have the ability to "play dead" if startled by a large predator (such as a human). If they are then picked up by the unsuspecting animal tracker, they will deliver their painful bite and then escape. There is a breathing tube from the abdomen that can be used to replenish air supplies. Unusually for invertebrates, the male looks after the eggs that the female lays. He doesn't have much choice: she lays them on his back and sticks them there with waterproof glue.

PHOTO COURTESY OF BIO-IMAGE NET