|from the July 21, 2008 Newsletter, after a visit to Land
Between The Lakes National Recreation Area in western Kentucky:
LITTLE RED DOTS IN THE ALGAE
With my nose right at the scummy water's edge I saw tiny, red, globular items sailing through the water between algae strands much faster than you'd think such tiny spheres could swim. With sweat and a world of glare in my eyes I couldn't see the blobs well but I knew they were water mites, somewhat related to ticks, and even looking a little like them. My close-up of a patch of red-dotted alga scum shows them suspended in their sparkling, bubbly green galaxy above. Many kinds of water mite exist but I suspect that these are members of the genus HYDRYPHANTES.
I read that water mites metamorphose through three active stages: larva, nymph (a special kind called a deutonymph), and adult. Larvae are distinguished by having six legs. They live free but eventually attach to immature aquatic insects where they become parasitic. I've seen aquatic insect larvae affixed with tiny red dots, so that was what was going on there. Once water-mite larvae engorge on their host they drop off, remain quiet a while, and then metamorphose into deutonymphs, which have eight legs. Deutonymphs as well as adults prey on small crustaceans or aquatic insect eggs and larvae. The deutonymph grows until it metamorphoses into an adult.
In my photo it looks like I have six-legged larvae. My Golden Guide called Pond Life says that adult water mites can reach 0.2 inch long (5 mm) and that's much larger than what's in my photo.