I actually noticed the rapid decline around 2000. Me and my sister would catch a "jar full" back in the 80s at my Grandpa's farm on any rainless summer night. There are many nights now where I don't see a single one!

Maybe a question for the Ph.D. entomologists out there --- but do Spotted Lanternflies compete for the same food sources as lightning bugs? Might explain why the fireflies are being weeded out.