Cassini periodical cicadas
The name Cassini periodical cicadas is used to group two closely related species of periodical cicadas: Magicicada cassini (Fisher, 1851), and Magicicada tredecassini (Alexander and Moore, 1962), a species essentially identical except for its 13-year lifecycle. The 17-year species is not called Magicicada septencassini because it was named prior to the 1962 paper.
The cassini males' courting behavior is unusual because large groups of cassini 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.
All Magicicada species have a black dorsal thorax with red eyes and orange wing veins. Cassini periodical cicadas are smaller than decim 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 (1958):
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 (so-called because it inspires both males and females to congregate) requires this synchrony in cassini-types for its success.
Periodical cicadas live in eastern United States east 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. 
Egg-laying by a large brood may cause many twigs to die off but does little long-term harm to mature trees.
- "Periodical Cicada Page". University of Michigan. Retrieved 10 June 2011.
- Carter, Janet L. Stein. "Periodical Cicadas". University of Cincinnati. Retrieved 19 June 2011.
- Capinera, John L. (2008). Encyclopedia of Entomology. Springer. p. 2792. ISBN 1-4020-6242-7.
- Alexander, Richard D.; Thomas E. Moore (1958). "Studies on the acoustical behavior of seventeen-year cicada" (PDF). Ohio Journal of Science 32 (2): 107–127. Retrieved 20 June 2011.
- Cook, William M.; Robert D. Holt (2002). "Periodical Cicada (Magicicada cassini) Oviposition Damage: Visually Impressive yet Dynamically Irrelevant" (PDF). American Midland Naturalist 147: 214–224. doi:10.1674/0003-0031(2002)147[0214:PCMCOD]2.0.CO;2. Retrieved 18 June 2011.