Endangered Species Biologist at Xerces Society for Invertebrate Conservation.

I have spent a lot of time identifying and annotating observations of Lampyridae (fireflies, lightning bugs, glow-worms), mostly in the US, but also in Canada, Central America and Mexico. Many firefly observations can only be identified to genus level, especially if they don't include photos of the underside of the firefly's body, flash pattern details, air temperature, and other contextual clues.

If you've caught the firefly bug, definitely check out the Xerces Society’s new Firefly Atlas, an initiative to collect data on threatened and data-deficient (as in IUCN Red List status data-deficient) species.

A helpful tool on the site is a filterable checklist of firefly species of the USA and Canada, which you can use to generate a preliminary list of species for your state, province or territory.
Training video for how to do Firefly Atlas surveys and Firefly ID videos

Firefly anatomy and flash pattern terminology

Firefly photography tips for ID purposes

Some firefly guides, keys, and monographs