Why aren't there fireflies on the west coast?

Answer 1

Actually many firefly species live on the west coast, primarily in Oregon and Washington. Most, though, don't glow and that's a major reason you don't often notice fireflies along the West Coast.

A couple of firefly species (Zarhipis integripennis and Pterotus obscuripennis), in Oregon do glow however.

Answer 2

Fireflies are more commonly found in the eastern and central parts of North America due to differences in climate and habitat. Fireflies thrive in the humid conditions found in the eastern United States, while the drier climate and urbanization of many areas on the West Coast are less conducive to their survival.