Sunday, July 1, 2012
As I scoped the animal through my lens, I noticed it carried some baggage. Those little globules on the underside of the bluet's thorax are water mites, in the genus Arrenurus (presumably). These mites are parasitic on damselflies, and can occur on their hosts commonly. Studies of water mite/damselfly infestations have found anywhere from 10% to over 50% of a given damselfly population can be parasitized by mites. The mites are not benign; their purposes for attaching to a damselfly are twofold. One, the mite taps directly into its host and extracts bodily fluids, and the greater the number of mites that are present, the greater the reduction in fitness of the damselfly. Two, the damselflies essentially serve as winged taxi cabs, hauling the water mites to new areas that can be colonized. Flighted insects, and birds, play an enormous role in the dispersal of other organisms, whether they want to or not.