Mid-Atlantic Aquatic Invertebrates

A family-level key from the Maryland Department of Natural Resources 
Introduction to using the key
Insect Groups
Order Coleoptera Beetles
Order Collembola Springtails
Order Diptera True flies
Order Ephemeroptera Mayflies
Order Hemiptera True bugs
Order Lepidoptera Butterflies and Moths
Order Megaloptera Alderflies and Fishflies
Order Odonata Danselflies and Dragonflies
Order Plecoptera Stoneflies
Order Trichoptera Caddisflies
Non-Insect Groups
Class Annelida Leeches and Worms
Class Bivalvia Clams and Mussels
Class Crustacea Crayfish, Scuds and Sowbugs
Class Gastropoda Snails
Literature cited

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