Where I grew up, the city wanted to hire a bunch of trucks to drive around spraying malathion into the air. They had a vote, and the town voted overwhelmingly that, fuck no they did not want that, please don't do that, that sounds awful. Then they did it anyway.
Same thing; now there are pretty much 0 fireflies.
Blame the raking of the leaves. No leaves in fall means no place for the eggs to be laid and no place for the larvae to grow. It's another casualty to grass lawns. A "clean" nature is a place where nothing has room to thrive.