When Arizona cicadas sing, summer rains are near

Today’s question: What causes the cicadas to emerge at this time of year? This is the gist of a lengthy voicemail that went on and on about June bugs and Barbados and was too long to use here in its entirety. It is a timely question because our cicadas are a sure sign — as if we needed one — that the monsoon is upon us. When the cicadas sing, the rains are coming.

We are a state rich in cicadas, about 50 species. Ours are not the 17year variety you might have known in the East or Midwest. Arizona cicadas are on two- or three-year schedules, staggered so some of them appear every year.

Why they emerge at this time of year is not 100 percent clear, but it probably has something to do with ground temperatures or the moisture contents of the atmosphere.

Cicadas spend most of their lives underground, living on the sap they suck from tree roots. When their time comes, the nymphs burrow their way to the surface, glom on a tree, shed their old skins and emerge as adults.

If you are interested, you could see step-by-step photos of this shedding and emerging process at arizona beetles bugs birds and more.blogspot.com.

Once they emerge as adults, the males raise a racket to attract females by flexing a pair of membranes on their undersides to create a clicking noise that is amplified by a hollow cavity in the body.

You can read more nifty stuff about cicadas, including how they use a kind of evaporative cooling to help them avoid predators, by digging around at uanews.arizona.edu.