Thursday, June 24, 2010

LOOK FOR (and listen for): Dog-Day Cicadas

Those of you who lived in the DC area in 2004 remember all the hubbub about the 17-year cicadas (who were making quite a hubbub themselves that summer). But you don't have to wait until 2021 to see another cicada -- some come out every summer.

Cicada lyrica by DaynaT
The annual "dog-day" cicadas actually spend 2 to 3 years in a nymph stage before coming out to fill your evening with the sound of summer. The nymphs hang out under the ground, feeding on tree roots. Then one day they get an adolescent itch to grow up. The next thing you know, they've come above ground, attached themselves to some handy object (often a tree or fencepost), split open their exoskeleton, and emerged as an adult. They emerge all light green and soft, but harden up over several hours. (This is very cool to watch; I highly recommend it if you ever get the chance!)

Emerging cicada
Emerging cicada by Anita Gould
Of course, their job as adults is to mate. Toward that end, male cicadas make an enormous racket -- some individuals have been recorded at over 100 decibels, around the same noise level as a lawnmower or chainsaw, and among the loudest insect noises in the world. (The Latin name for the genus suggests something a little gentler -- Tibicen means "flute-player.")

Different species each have a different sound, which helps them to find appropriate mates. Three of the earliest to come out in the Mid-Atlantic area are Neocicada heiroglyphica (sound), Tibicen lyricen (sound) and Tibicen tibicen (aka chloromerus) (sound).

Because they're active mostly at night, and up in the treetops, it's not that common to actually see cicadas. The ones we've seen most have been either a) molting or b) bird food. But keep an ear out and you're sure to hear some soon in the evenings.

Cicada encounter by Oakley Originals