Whether you call them lightning bugs or fireflies, the little insects of taxonomic family Lampyridae are fascinating as they light up the night. A couple thousand species exist, and dimorphisms or sexual differences differ from one species to another. But they do have definite differences that you can see if you know what you’re looking for.
Male and female fireflies have different habits that can give you clues to gender without you having to catch them. Males blink their lights as they fly about, signaling location and availability to potential mates. Females blink back if they’re interested, but they generally sit still in the bushes in reply. This method isn’t perfect, since sometimes the boys will start blinking before they take flight or after they’ve landed for the evening.
To be sure about the gender of a lightning bug you’ll need to catch it and look at the belly. Male Photinus firefly light organs are in the last two segments of their abdomens, while females’ light organs are only in the second-to-last segment. Male Pyractomenas look like Photinus, but females have two tiny light spots on each side of the last two abdominal segments. Research the types of lightning bugs in your area to discover other gender differences that may help identify males from females. Collect a specimen or 20 and seek an expert with your state's university extension agency.