Very long thorax. Much bigger/longer than fireflies usually seen here in July.
Some were flashing when I first got there at 8:45 with sunset at 8:08. Most were low to the ground to maybe two meters above and most stuck to the shaded areas along a slough. Flash images are 10 second exposures. Specimen was not measured but was ca. 1cm. Many were still flashing when I left ca. 9:15 but I think peak was around 9. There were well over 100 here and I'll bet if the slough was followed that there'd be thousands along it.