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Wednesday, Oct. 24, 2007

ANIMAL TRACKER

Little red damselfly


* Japanese name: Beni-itotonbo
* Scientific name: Ceriagrion nipponicum
* Description: The clue's in the name: This insect is small (just 35 mm long) and red — although the females, which are a slightly duller orange, or even brown, don't sport the vivid vermilion of the males. The four wings are held folded at rest over the abdomen like all damselflies.
* Where to find them: Well, these days, the little red damselfly has become scarce. It lives on in still water across Honshu, Shikoku and Kyushu, but many of the ponds where it lived have been reclaimed, polluted or overwhelmed with non-native fish. These factors have driven down the numbers of this damselfly, which is now extinct in many parts of the Kanto Region, though it can still be seen in central Tokyo — it is (along with several other dragonfly species) abundant in the gardens of the Imperial Palace. The insect is a weak flier, staying low to the water surface, and much prefers to fly only in warm and calm weather.
* Food: Other flying insects. Tiny flies and midges. Being such a weak, low-flying insect, the little red damselfly doesn't have many prey options.
* Special features: On such a small animal, you wouldn't expect there to be much room available for passengers. Yet tiny water mites hitch rides on the damselfly's body, clearly illustrating the universal nature of parasitism: parasites are everywhere, nothing can escape being parasited. Studies have found that 98 percent of little red damselflies are parasitized by even smaller water mites, which fasten to the exoskeleton and suck their blood. It's no joke carrying mites — although the parasites don't seem to affect the lifespan of the insect, parasitized males are much less likely to get mates. However, the female mates of those that do pull it off lay eggs in debris in ponds and bogs. The eggs hatch after about a month, and the tiny, 16-mm-long larvae develop over the next two years.

PHOTO COURTESY OF BIO-IMAGE NET



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