As in, well-educated regions will use “lightning bug”, less so ones “lightening bug”? Or was that an attempt at levity?
I started a thread at the beginning of the summer about lightning bugs (the usual local term, although fireflies is also used) and how few there seemed to be in NE Ohio this year. Many people from elsewhere in the country said they had plenty, though. It’s been pretty dry here until about two weeks ago, so I’m guessing there’s a connection.
Ah, here it is: Where are all of the fireflies/lightning bugs this summer? - Miscellaneous and Personal Stuff I Must Share - Straight Dope Message Board
I realize that it’s just a Staff Report, but am I the only one who thinks that this issue could have been tackled with a little more scientific rigor? I realize that it would be difficult to verify the central assertion (that there are fewer fireflies in Indianapolis today than there were 50 years ago), but as far as I can tell **Doug ** didn’t even attempt to find out if any of the possible explanations were more or less likely. Some assertions (e.g. “I’ll bet that Indianapolis in the last three years or so has been a lot warmer than it was back in the 50s, and very possibly drier.”) could have been easily established with a little legwork. I’m sure there aren’t mountains of data on the matter, but doesn’t the Dope deserve better than, “here’s what I can come up with off the top of my head.”
I’d like to add one other possible factor to Doug’s list: observer bias. I don’t see nearly as many lightning bugs as I used to, but then I don’t spend nearly as much time outdoors in the evening as I did when I was a youngster.
Here here; with all due respect, this was a rather lifeless effort.
Although I agree it would be difficult to verify the central assertion, I’d personally like to know if there is or is not a general decline in firefly population. Surely someone has studied the insect in detail…
Actually, click beetles are in the family Elateridae, not Lampyridae. There are bioluminescent click beetles, however, which may be where the confusion arises.
Properly speaking, glowworms are classified in the family Phengodidae.
Actually, we on the west coast do have our own lampyrids; the problem is that our most common species are diurnal and don’t produce light! In California, we have fireflies of the non-luminescent genus Ellychnia, for instance.
According to this site, there are luminous fireflies in British Columbia (e.g. Photinus ardens and Photuris pennsylvanicus), but your most common species also belong to the aforementioned genus Ellychnia.
Aw, wish I could share them with you. I don’t think they’d mail real well, though. 
They are enchanting, too. Fun to catch. I’ve taught my grandson not to grab them when trying to catch one, but rather to scoop them out of the air by opening your hand and gently coming up from underneath them in flight. They land on you, and will find the highest point from their new-found landing spot to take off from, thus giving you time to check them out.
We don’t keep them. We’re catch-and-release folks. 
A friend of mine who’s a scientist (but not Bio) said he’d read some speculation that srtifical light interferes with lightning bug’s reproduction…
Obviously, where theres lots of people, theres the most artificial lite, so maybe we’re only noticing a decline in L.bugs in high people population areas. Or maybe the reproduction thing only affects certain species (dominant in certain areas, like Indiana) ??
Just speculating…
Lightning bug to light bulb: Hey, baby, you live around here often?
A little more information on the subject:
I attended the University of Florida - my favourite class was Dr. Lloyd’s evolutionary biology course (using the evolutionary and biological history of fireflies, his expertise, as an example).
I only mention this as 11 years ago when I took this class he was looking into the population issue - anecdotally around Gainesville, Fl the places he’d take his classes to observe various species were becoming more and more limited. We could not even find some of the species prevalent in prior years.
I’d guess if he’s saying the populations are diminishing that they are. He frequently travels to various sites around the world to observe what’s happening.
I have seen one “glowworm” here in CA, apparently a larval bettel?
The California glow-worm (Zarhipis integripennis) is a beetle in the family Phengodidae. Both the larvae and females are luminescent; the females are larviform, so it could have been either a larva or an adult female.