Back in 2017, M and I went down to the
Metroparks at dusk to watch the fireflies come out en mass. I don't recall that we've done that since, but this summer we haven't had to. The fireflies have arrived earlier this year (probably because all the spring/summer things are three weeks earlier), and they have been all over our yard.
We've taken Birdie outside nearly every night the past week to catch fireflies. We've got a big plastic couscous jar with some wholes punched in the lid that Birdie can carry without fear of breaking, and we try to fill it up with fireflies. Birdie can't quite catch them herself yet, but she is very good at pointing at them so M or I (usually M) can snag them and put them in the jar.
Once a sufficient number have been caught we bring them inside and let the fireflies blink in the jar during bedtime. Once stories and singing are over, the fireflies are repatriated to the outdoors. Honestly, I think Birdie likes catching them more than watching them in the jar.
One day M would like to go see the synchronized fireflies down in the Carolinas. We have regular old unsynchronized fireflies, which are pretty great.