The cicadas I've heard this summer are annual guests. They emerge in the summer from their larvae stage under the ground and immediately crawl, climb, or fly clumsely to the closest plant, tree, building, etc. and begin singing, and singing, and then singing some more. There are periodical cicadas that emerge in the midwestern states on a 13 or 17-year cycle. Last summer (2007) Illinois was lucky #17 for the cicadas. If Lynn and I are still living in Illinois in 13 or 17-years, we will be investing in a few good pairs of ear plugs so we can sleep at night.
As with crickets, it is the male cicadas that ‘sing’ to entice the female cicadas. Large groups of males clump together. The loud(er) the noise the more females they attrack. All the loud racket disrupts the birds and other insect or animal species that might try making a cicada sandwich for dinner. (It is the usually the early cicadas that are gobbled up by dogs, cats and the birds. But, there are sooo many new cicadas (even when we are not on a 13 or 17-year cycle) that emerge every day that the dogs, cats and birds are sick of them and leave them alone. ) The louder they sing, the more females they attract. It’s a stereophonic symphony of sorts. It will seem like one tree will vibrate and sing, a neighboring bush will pipe in until the whole day or night sky is filled with the rattling boisterous music or noise of the cicadas.
The cicadas are buzzing their last breaths as we approach fall. They will all die out until next summer's generation appears and begins their energetic and earsplitting 'wind pipes of love'.