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Macroinvertebrate Groups Stream Insects, Crustaceans, and Gastropods

Mayfly Stonefly

Dobsonfly (Hellgrammite)

Riffle Beetle

Group 1. These organisms are generally pollution intolerant or sensitive species. Their dominance generally signifies GOOD WATER QUALITYGOOD WATER QUALITY.

Water Penny Caddisfly Gilled Snail

(Shell opens to the right)

Dragonfly

Group 2. These organisms are somewhat pollution tolerant and indicate FAIR WATER QUALITYFAIR WATER QUALITY.

Damselfly Fishfly Larva

Beetle Larva

Bar lines indicate relative size

Group 2. Continued Somewhat pollution tolerant and indicate FAIR WATER QUALITYFAIR WATER QUALITY.

Group 3. These organisms are pollution tolerant and their dominance usually indicates POOR WATER QUALITYPOOR WATER QUALITY.

Alderfly Crane Fly

Sowbug

Crayfish

Clam

Scud

Illustrations by: Arwin V. Provonsha, Aquatic Entomology, 1981 Amy Bartlett Wright, A Guide to Common Freshwater Invertebrates of North America, 2002

University of Arkansas, United States Department of Agriculture, and County Governments Cooperating

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Leech

Blackfly Larva Midge Fly Larva

Pouch Snail (Shell opens to the left)

Aquatic Worm

Other Snails