Friday, September 20, 2013

Dog Day Cicada



I guess it is now officially the dog days of summer as we found a lot of dog day cicadas on La Petite Gemme Prairie Thursday, clinging to the stems of the chest high grasses and forbs.  The prairie was burned last January and the heavy burst of midsummer rain had worked its miracle.

"Dog day cicadas" are members of the genus Tibicen, named for their abundance in late August through September in the hottest times.  They make a buzzing sound when they take off on short flights when disturbed and create a loud grating sound when held.  This one talked to us throughout the photographic session.

These are called annual cicada as, unlike the 13 and17 year periodic cicada, they appear annually.  This however is deceiving as the life cycle of an individual is over two to five years.  Like their periodic cousins, they lay their eggs on twigs and the larvae emerge, leap off into space and land on the ground where they dig in.  They then burrow into roots to suck sap for the next few years until they mature and emerge, crawling up a tree or post and hanging on tight while the adult emerges and flies off, leaving the empty shell of dried skin to puzzle or delight a lucky child.  These cicada appear to be annual because each year some are emerging and mating.

Last week's "What is it?"
Here it is full size













Many cicada species live in woodlands, as evidenced by the constant buzz along Bull Creek this month.  Our specimen above is the exception.  The colorful bush cricket, Tibicen dorsatus, is also called Grand Western Cicada and Splendid Prairie Cicada.  It is usually found on prairies and open grassland between the Rockies and the Mississippi River.  While not threatened, it is commonly found in isolated pockets as mowed lawns and monoculture fields are not to its taste.

Tibicen dorsatus
As usual, as soon as I identify a distinctive insect, I come across a newly described species which it can be confused with.  Now T. tremulus has been officially recognized as a separate species, identifiable only by a slightly different shade of the timbrel, a vein on the wing, and a distinctive song.  Only the male cicadas sing.  The sound our T. dorsatus makes is here and you can compare it to this T. tremulus recording.  Nature is never satisfied with the status quo, continually evolving which keeps a lot of entomologists employed, when they can find work.

Detailed Tibicen anatomy link

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