For definitive identification of many bee species, close inspection of insect morphology (wing veins, leg parts, etc.) is required. This necessitates having specimens in hand to observe features under a microscope or through a hand lens. Numerous entomology texts detail how to collect and curate bees and other insects.
Some excellent online tools are also available, including the Bee Genera of Eastern North America by Sam Droege and Jelle Devalez.
The following web-based pictorial guides help in basic identification of common bee groups:
- AMNH Pictorial Guide to Common Bees in New York City
- Discover Life bee species guides cover all eastern North American bee genera. These link to associated species pages featuring dynamic maps, images, and descriptive text
- Bryn Mawr College and Rutgers University Native Bee Benefits, which includes a pictorial guide to important pollinators for farms in New Jersey and Pennsylvania (see also http://www.extension.org/pages/26310/identification-of-native-bees)
- Collecting and Identifying Bees (Cornell University's Bee Health website)
- Great Sunflower Project bee guides (this is not a regional guide but has useful information)
In addition to physically collecting insects, digital photography is increasingly being used to identify some bees. Digital photos of NYC bees (and of any North American insect) can be submitted to BugGuide for identification. Provided that relevant structures of the insect are in focus, bee and other insect taxonomy experts should be able to identify the insect in your image. BugGuide guide pages cover most species regularly identified from NewYork City.