Stoneflies Pteronarcys sp

Description They are all freshwater inhabitants as larvae. As a group they are close relatives of the cockroaches and have retained the primitive condition of possessing tails but demonstrate the advanced ability to fold their wings over the back of the body. Their common name undoubtedly is derived from the fact that individuals of many common species are found crawling or hiding among stones in streams or along stream banks. 

Distribution Close to 500 species are represented in North America. Many stoneflies are known as clean-water insects, since they are often restricted to highly oxygenated water. As such, some are excellent biotic indicators of water quality. Adults of stoneflies can be found throughout the year, some being adapted for winter emergence. (Aquatic Entomology, 148). 

Larvae are slender, commonly cylindrical and slightly curved forms that usually measure 2 to 20 mm but are occasionally larger. Body has a pair of pro-thoracic prolegs and a pair of terminal prolegs. Terminal segment usually has a short dorsal pair of tubercles or projections, each with a variable tuft of hairs (dorsal pranal brushes). 

Larvae of this very large, common, and geographically widespread family are distinctive. 

Snails (Physa integra, P. heterostropha, Amnicola limosa)  

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