1. Troutnut Forum
›
2. Photography
›
3. Glossosoma

These are similar to the Agapetus I posted earlier but are easily differentiated by not having sclerites on the mesonotum. In this area they show marked differences in habitat, Agapetus being found in the mainstem and larger tributaries of the Russian River while Glossosoma is found in the smaller tributaries. Both are found on a substrate of clean, unembedded gravel and cobble. Glossosoma prefers streams with cooler temperatures and more canopy than Agapetus. Glossosoma is most common in riffles while Agapetus prefers glides and areas just above riffles. Both show up as larvae from March through May.

The thread on Agapetus is here http://www.troutnut.com/topic/8638/Agapetus-larva-and-pupa#42086

An article on fishing the larvae, pupae and adults of Glossosoma by Rick Hafele can be found here http://www.laughingrivers.com/rick-glossosoma.html

Mark,

Wonderful stuff, as usual!

Spence

Millcreek - your mature pupae are females - you can see that the mid-leg femur and tarsi are flattened and broad. They use them like oars to "swim/scull" through the water during emergence. I can also see that the abdomen ends in simple tubular segments rather than the complex segment of the male. creno

Spence - Thanks, hope they don't send you off on another fly tying spree.:)
Mark

Creno - Do the adult females also use the flattened legs during oviposition or are they "bombers" or "dippers"? Thanks for the info. Millcreek

Mark, I'll second Spence's comments again - excellent photos! And you must have some interesting geology in the area of these streams, from the rather unusual looking grains they make their cases out of - reminds me of those folks who purposely rear caddisfly larvae in aquaria stocked with colored sand grains or even small fragments of precious metals to make natural jewelry.

Jonathon

Jonathon, Thanks. As for the geology it's mostly sandstone but there are faults along the stream that yield schist and ultramafics and there are some veins of quartz here and there as well. And yeah, I've seen some of the jewelry made. Some pretty neat stuff at this site:http://www.cabinetmagazine.org/issues/25/duprat.php
On a related note, we had some entomologists in this area who were interested in finding out about the movements (or lack of them) of Gumaga larvae in a couple different areas of a stream. They reared large numbers of larvae and gave them glitter of various colors to track them more easily. Link is here: http://stroudcenter.org/about/pdfs/Jackson_etal_1999.pdf

Wow Mark, way cool links! I have actually never seen the caddisfly jewelry thing in action until now, and that is really amazing...is art imitating nature, or nature imitating art? Or is it all merely in the eye of the beholder, Mother Nature's just doing her job and it's us overly-brained humans who get all fascinated and emotional about it, which is so much fun anyway...

This reminds me of an experiment I have heard can be done with crayfish. Apparently, these critters maintain their balance in the world through a small organ that contains grains of sand suspended from threads. The threads of course hang downward with gravity, activating nerves in this little chamber that keep the crayfish oriented upright. Perhaps a bit analogous to our own inner ear hairs in a fluid-filled chamber? Well, if you let a crayfish shed in an aquarium filled with iron filings, they apparently incorporate new sand grains into a new chamber when they shed, and if they get iron filings instead, you can make them turn upside-down with a magnet! So I've heard, never seen it demonstrated...

Jonathon

Jonathon - I'd never heard that about crayfish balance organs and I've got to admit my first reaction was "Nahhh, something wrong with that!" but I started hunting around and found several references to statocysts (the balance organs) and apparently the movement of crayfish can be influenced if you replace the sand grains with iron filings. Here's a link:http://link.springer.com/article/10.1007%2FBF00657338#page-1
Click the tab on the upper left that says "Look Inside" to see the first couple pages of the paper.

Mark