Oh dear... You know I hadn't really paid much attention, but now that you bring it up, it does seem like we have a lot fewer fireflies than we used to. I've been thinking it was just because of the rain.
I hadn't heard this before, so I will watch out more now.
I looked up their habitat to think about could I provide better for them and discovered something else I didn't know -- firefly larvae are said to eat slugs and snails! (oops obviously I hadn't read Scott's links yet!
) Fireflies need some standing water, even if just a little, could be one more reason they are having trouble, since we are all busy eradicating standing water due to mosquitoes. For the larvae they also like rotting wood or forest litter. For the adults they like long grass:
"Fireflies also love long grass. they're nocturnal, and during the day they spend most of their time on the ground. At night, they crawl to the tops of blades of grass and fly into tree branches to signal for mates. Long grass conceals the fireflies better and allows them a better vantage point for signaling at night, and over-mowing your lawn may disturb your firefly population." https://www.firefly.org/firefly-habitat.html
The grass and all the rest would have to be without chemicals of course.
No wonder they are declining. I have the forest litter and I have (unfortunately) tons of standing water with a big pond at the bottom of my hillside, but I'll have to think about whether there's somewhere I can leave a bit of grass for the fireflies.