How many species of periodical cicada are there?
There are three different species of 17-year periodical cicada that will emerge in 2004: Magicicada septendecim, M. cassini, and M. septendecula. There are also four species of 13-year cicadas: Magicicada tredecim, M. tredecassini, M. tredecula, and M. neotredecim, but these species will not be found during the 2004 emergence.