Good identification keys are hard to come by. Here are a few I’ve gathered while trying to identify my little beasties:
Insects/General
- American Insects by Stephen Cresswell (great photographic reference)
- Austin Bug Collection
- Bug of the Week – University of Wisconsin
- BugGuide.Net – Iowa State University
- Bugphotos.net – Bugs and Critters in my Florida Backyard
- Greg’s Moths – Pickaway County Moths and Beyond (Greg Hodge)
- Florida State Collection of Arthropods – Museum of Entomology Gainesville
- Keys Moths – Moths of the Florida Keys
- Taxonomic Keys, macroinvertebrates of Florida – Florida Department of Environmental Protection
- Texas Entomology – Compiled by Mike Quinn
Specific Insect Families
- Ants of the United States – antwiki.org
- Antkey.org (an excellent insect anatomy primer)
- Antweb.org
- Bee Genera of North and Central America – Smithsonian Institution Press (PDF)
- Beetle Fauna of Germany – Kerbtier.de
- Burying Beetles of Minnesota – Field Ecology Blog
- Butterflies of the Rainforest Exhibit at the Florida Museum (Butterfly search here)
- Caddisflies (Trichoptera) of Florida – Center for Systematic Entomology
- Carabidae of Florida – University of Florida (Ground beetles and tiger beetles)
- Caterpillars on the Folidage of Conifers in the Northeastern United States – USDA, US Forest Service (PDF)
- Celethemis Dragonflies (Pennants) of the Mid Atlantic Region – Jim Brighton
- Checklist of the Membracidae of Florida – Museum of Entomology – Gainesville
- Cicada Mania – not so much a key as a way of life
- Deltocephalinae Leafhoppers of North America – James N. Zahniser
- Florida Damselflies and Dragonflies – Jeffrey Pippen
- Florida Praying Mantids (Key) – University of Florida
- Florida Water Bugs – Johnepler.com
- Geometrinae – North American Emerald Moths – Friends Central
- Grasshoppers of Florida – lepscience.com
- Grasshoppers of Florida – University of Florida
- Green Lacewings of Florida – University of Florida
- Guide to the Mayfly (Ephemeroptera) Nymphs of Florida — State of Florida Dept of Environmental Protection (PDF)
- Guide to the North American Membracidae (draft) — bugguide
- Biology and illustrated key for the identification of twenty species of economically important noctuid pests – A. D. Oliver, LSU State Commons
- Key to the common surface dwelling Collembola from North America – by Frans Janssens on collembola.org
- Manual for the Identification of Ground Beetles of Florida – University of Florida Laboratory (requires Scribd account)
- Mayfly Central – Purdue University
- Nelson’s Butterfly Page – Nelson B Dobbs
- Photographic Guide to Common Mosquitoes of Florida – Michele Cutwa & George O’Meara, University of Florida Medical Entomology
- Planthoppers of North America – University of Delaware
- Scarab Beetles of Florida – UF online library (full book)
- Reduviidae – Biological Survey of Canada (Assassin Bugs)
- Robber Flies of Florida – Steve Collins
- Stink bugs and parent bugs of Ontario – Canadian Journal of Arthropod Identification
Birds
- AllAboutBirds.org – The Cornell Lab
Herps / Lizards
- Anole Lizards of South Florida – iNaturalist
- Florida Lizards – Florida Museum
- Visual Guide to Florida Snakes – Florida Museum
- What Snake Is That?
Snails / Slugs
- Slugs of Florida – University of Florida
- Terrestrial Mollusc Tool – University of Florida
- Tree Snails of Florida Identification Key – University of Florida
Spiders
- Jumping Spiders of the World – jumping-spiders.com
- The Peckham Society – informal alliance of jumping spider enthusiasts, with a great index of individual species articles
- Spider Identification Guide – Gerald D Wegner via BASF
- SpiderID.com
- Contributions to the taxonomy of the long-jawed orb-weaving spider genus Tetragnatha (Araneae, Tetragnathidae) in the Neotropical region, with comments on the morphology of the chelicerae — Zoosystematics and Evolution 95(2): 465-505
- USA Spiders – spiders by state, by family, sorted all sorts of ways
- World Spider Catalog – Natural History Museum Bern
Extremely General
- Field and Swamp – dpughphoto.com
- Florida’s Nature (lots of plant photos)
- Tom Murray Photo Database
Other Keys
- A Nature Journey (European flora/fauna)
- Backyard Arthropod Project
- Big Thicket Critters (insects of Texas)
- A Chaos of Delight (A photographic guide to the soil mesofauna)
- Field Oriented Keys to the Florida Lichens – Boise State University
- Lusoborboletas de Portugal (Butterflies and moths of Portugal) – Pedro Pires
- Micro-Moth Families — Britain and Ireland — Garden Moth Scheme
- Wildflower Search
- Zirqui All-Diptera Biodiversity Inventory (Flies of Zurqui de Moravia)
Other Interesting Literature
- Florida Entomologist magazine (open access)
- Living with Insects blog
- Songs of Insects
- The Incorrigible Entomologist – Brandon Woo
- Understanding Mayflies – Fly Fisherman
- World Spider Catalog – less a key than a collection of journal articles