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Friday, Aug. 24, 2001
By ROWAN HOOPER
* Japanese name: Shiokara tonbo * Scientific name: Orthetrum albistylum speciosum * Description: A fast-flying dragonfly 48-57 mm long. Males have a pale-blue body; the end of the abdomen is pointed and black, and is equipped with a pair of clasping appendages. Females are usually a brown-yellow color, but there is much variation. The end of the female abdomen is broader than in males; it stores eggs and fires them out in a scatter pattern. As males mature, a waxy white substance develops on their abdomens -- this explains their Japanese name, salty dragonfly. In English, these dragonflies are often called darters because of their habit of darting out from perches to feed. * Where to find them: In rice paddies, swamps, ponds, fields, shrines, temples and city parks from April to October. They like bright areas. Females lay eggs in shallow water while hovering, and a male usually guards her. * Food: Other flying insects. All six legs are held together to form a basket, which is used to scoop insects out of the air. * Special features: Males are unusual in that they have two sets of genitalia. The testes are located at the end of the abdomen, and a secondary set, containing a specialized penis, is located at the junction of the abdomen and thorax. This is why dragonflies have to form a wheel shape when they copulate -- the female is caught by the neck (in midair) by the claspers on the male's abdomen and swung around to engage with the penis. Before he inseminates the female, the male scrapes out sperm the female has stored from previous matings, using hooks and bristles on his penis.