The Great Clark Lake Caddis Fly Hatch 2008

Many of you know that John and I are fascinated by aquatic insects. In addition to providing John work for two years, aquatic insects are great fish food (frequently found in the fish guts that I analyze for my PhD), used as indicators of water quality, and have fascinating life histories.

Caddis flies are especially interesting to me because they have a larval aquatic stage, in which they look something like a grub (but a little longer and not so disgusting), and they build these elaborate cases in which to hide from predators like fish. Sometimes the cases are built out of sand, sometimes out of wood, and sometimes they weave elaborate nets to filter out particles from the water on which to feed. Each species has a specific style of case it builds.

Anyway, a few days ago, there was a gigantic hatch of white caddis flies on Clark Lake. I have never seen so many millions of bugs emerging all at once. For those of you less familiar with the Order Trichoptera, the caddis fly begins its life cycle as an egg that hatches to a larvae. The larvae survives for many months, feeding and growing, and eventually metamorphoses into a pupae that swims to the surface of the water to molt into the adult, winged form. The adult lives for a few days, mating, laying eggs, and then dies. By undergoing these life cycles en masse, the emerging insects overwhelm their predators and ensure that many will survive to reproduce, as well as increases the probability of successfully finding a mate.

If this hatch was any indication, caddis flies are doing quite well in Clark Lake.

All those white specks are caddis flies. The adult form looks something like moths, and have really long antennae.