Wednesday, August 15, 2012

Dragonfly Book and Water Mites

I have written a book called "Two Years Among the Odonates." I describe the dragonflies and damselflies I have encountered during my first two years of odonate watching. Most of the material has appeared in this blog. The book is published by Anyone interested can click on this link and see a 15-page sample of this 164-page book. Those wishing to purchase the book have choices in format (hardcover, softcover, etc.) and prices. Unfortunately the book is relatively expensive since it is produced on a per-order basis and it is all in color. Orders are processed quickly. I put another link to the book at the top of the right-hand column of this blog. Note that the book is also available at a greatly reduced price as an eBook on iBooks for the i Pad.

A few days ago I blogged about not finding water mites on my dragonflies. This lapses has been remedied by eagle-eyed Scott King, who spied a parasitic water mite larva on a photo I have previously posted. Look closely at the bottom (dorsal) edge of this Cherry-faced Meadowhawk's thorax (body). Another larva is attached on the bottom end of the abdomen (tail). Sometimes huge numbers of larva infest a single host.
Water mites are the only truly aquatic spiders. Adults are round, often red, with eight tiny legs. They are often abundant in lakes. A complicated vocabulary describes the mite life cycle. Basically, the adults, who are predators of various immature aquatic insects and micro-crustaceans, lay eggs in the lake.  The eggs develop into the parasitic larva that attach to a variety of insect orders, including flies, beetles, and dragonflies. These parasitic larva obtain nutrition from their hosts, but, perhaps more importantly, they are dispersed to new ponds and lakes. Once in the new habitat, the larva continue through a second form that resembles the adult but which do not reproduce. Finally the adult stage is reached and the little arachnids breed. For a more detailed description of the water mite life cycle, see "Water Mites of North America."

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