Decoding Firefly Flash Codes

photo: http://www.flickr.com/photos/theloushe/3622541416

If you missed the meteor showers due to rain or moonlight, don’t despair – you can catch the nightly firefly shows. Fireflies fill the dark spaces between the stars with their blinking lights. Watch them long enough and you begin to see that there are different flash patterns. Some fireflies blink many times in quick succession, dit-dit-ditting a zigzag through the dark. Others flash a couple of long, slow blinks and pause, as though waiting for a response. Perhaps they are; within seconds flash-code messages are returned from the tall grass.

With as many as 20 to 30 species in our region, all sharing the same habitat, the nighttime airwaves can get crowded with messages. To reduce confusion, each species has developed its own unique flash code. One species might signal with a long flash followed by two short flashes, while another uses three flashes in a row.

Just as important as what fireflies say is how they say it. Some species hover in place as they flash; others write their love messages in glowing curves as they fly. While some fireflies flash their love messages early in the evening, others don’t even file their flight plans until the night’s half over.

Fireflies divide the night sky spatially as well. Some species fly low, right over the grasses, to flash their messages. Others fly at shrub-height, and even others fly among the treetops. Then there’s color – some fireflies flash greenish-yellow while others produce an orange glow.

To find out more about the fireflies in your back yard all you need is a notebook and pencil, a flashlight covered with blue cellophane (fireflies don’t see blue) and a warm night for watching. Spend a few minutes watching the lights, then jot some notes down. If you can distinguish individual fireflies you might be able to decode their flash patterns. Some of the things you’ll want to keep track of are the colors of the flashes, the pattern (length of flashes), how many flashes are in a series and the interval of time between flashes. If you don’t have a stopwatch you can count seconds by saying “one fire fly, two fire fly…”

You will also want to note such things as time of night you see that particular pattern, how high the male flies and what his flight pattern is, where you saw the responding female, and the temperature.

For more on fireflies, check out Firefly Facts