The name Cassiniperiodical cicadas is used to group two closely related species of periodical cicadas: Magicicada cassinii having a 17-year lifecycle, and Magicicada tredecassini, a species essentially identical except for its 13-year lifecycle. Courting behavior of Cassini cicadas is unusual because large groups of males may sing and fly together in synchrony: that is, bursts of sound, as thousands of males sing in unison, alternate with silence, as clouds of flying cicadas leave perches in unison, seeking a new perch before the next ensemble song.
Description
All Magicicada species have a black dorsal thorax with red eyes and orange wing veins. Cassini periodical cicadas are smaller thandecim periodical cicadas. The abdomen is black except for occasional faint orange-yellow marks on the ventral surface seen in some location. In a typical brood of periodical cicadas, decim and decula types will be present as well as cassini. The three different types have unique species song-types; they also tend to sing at different times of day, with cassini choruses most likely in mid- to late afternoon, later than decim or decula varieties. The cassini-type song consists of a series of ticks followed by a buzz; it has also been described as sounding like "someone trying to get a lawnmower started." Magicicada males seek out sunlit vegetation, where they typically gather with conspecific males to form large choruses, alternating singing behavior with short flights. Cassini-type males are unusual in synchronizing these behaviors, so that thousands of males sing their mating song in unison and then fly together. according to Alexander and Moore :
Almost every singing male in a woods containing tens of thousands of singers achieves synchrony with all the others, and the result gives the impression of a gigantic game of musical chairs. A treeful of these insects singing in synchrony is motionless when observed during the great burst of sound caused by insects buzzing together, and then becomes a frenzy of activity between buzzes with nearly every individual changing perches.
The "congregational" singing of males requires this synchrony in cassini-types for its success.
Habitat
Periodical cicadas live in eastern United Stateseast of the Great Plains. Cassini-type cicadas are especially common in the most southwestern populations and are the only 17-year cicada species found in Oklahoma and Texas. Cassini-type cicadas are most often found in deciduous lowland woods and flood plains, rather than the upland woods favored by other Magicicada.
Ecological impact
Egg-laying by a large brood may cause many twigs to die off but does little long-term harm to mature trees.
