significant numbers. It was also present in large numbers at the two 

 lowest stations. 



Insecta 



Tricboptera . The caddisflies are an order of insects that are 

 indicators of clean water with high dissolved oxygen content. They undergo 

 conrplete metamorphosis, progressing from egg to larvae to pupae to adult. 

 Four genera were selected as possible indicator organisms. 



Ochrotrichia belongs to the family Hydroptilidae, the "Microcaddis". 

 All members of this family are small. They build a tiny {2-k mm.) case, 

 shaped like a flattened bean, smd slit at each end. The case is usually 

 constructed of silk with saind or minute bits of rock adhering to the exterior. 

 When ready to pupate, the individual closes the slits at each end and com- 

 pletes its metamorphosis. 



Hydropsyche belongs to the family Hydropsychidae . This organ- 

 ism bviilds a net which it attaches to rocks or twigs so that the opening 

 is perpendicular to the stream flow. After constructing the net, the 

 larvae retreats into the hag of the net or under some nearby rock to await 

 food pajrticles which are swept onto the net. Hydropsyche is eua omnivore, 

 consuming euaything that is edible. When this organism is ready to pupate, 

 an elliptical dome-shaped cocoon is spun with pebbles and bits of rock 

 neatly fitted to the exterior. Only the bottom which is glued to a large 

 rock is left unadorned. 



Agapetus is a member of the family Glossosomatidae. This animal 

 builds a case shaped much like a tuzi^le shell out of small stones. The 

 elliptical dome-shaped case, with a flat bottom, has a bridge of small 



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