Caddisflies: Hydropsychidae

There has been a cry for more science. I can understand that. I've been a moody fuck recently, taking all my blog posts and turning them into a dropping ground for my emotional turmoil. Time for some entomophilly (some insect lovin').

The family Hydropsychidae is a large well distributed group of caddisflies. They are also my favorite, the one I have worked the most with, and the one that haunts my psychology the most. They are the net-seine spinning caddisflies, abundant in streams throughout most of the world.

The larva of a Hydropsychid is easily distinguished by the large number of filamentous gills on its abdominal segments, and by a fully sclerotised plate on the dorsum of each thoracic segment.

A typical hydropsychid:

http://www.sdgfp.info/Wildlife/Diversity/Digest%20Articles/caddis2.jpg (or would be if I could get the picture to work)

As I said, hydropsychids are abundant on stream bottoms throughout the world. They are retreat maker caddisflies, meaning they make a stationary hideaway out of debris and silk. An intricate seine net is positioned outside their retreat, facing into the current, and it looks very much like a fishnet. Debris and organisms are collected in the net, and depending upon the species, hydropsychs may be carnivores, herbivores, omnivores or dentritivores. The mesh size of the net tends to follow this trend: dentritivores have smaller mesh sizes while pretatory nets have larger mesh sizes. The mesh shape and size is also a function of the size and shape of the protrochantin, which is used in the spinning of the silk and net construction.

Hydropsychid larvae also have the unique ability among caddisflies to produce sound. They do this by rubbing their prothoracic legs along the underside of their heads, which have rows of stidulating ridges that produce a rasping sound. It is believed that this is used in territoriality in hydropsyches, as they are filter feeders and need a specific sized area in which to build their net retreats.

I think thats about all for now.