Cassini periodical cicadas
The Cassini periodical cicadas are a pair of closely related species of periodical cicadas: Magicicada cassinii (Fisher, 1852), having a 17-year lifecycle, and Magicicada tredecassini[a] (Alexander and Moore, 1962), a nearly identical species with a 13-year lifecycle.
Courting behavior of Cassini cicadas is unusual because large groups of males may sing and fly together in synchrony. Bursts of sound alternate with silence as thousands of males sing in unison, then leave perches and seek 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.
- While the original and correct spelling for Fisher's 17-year species is cassinii, with two 'i's, a large majority of publications have spelled the name cassini since the mid-1960s. However, the original spelling has been maintained throughout by taxonomic catalogues, and the rules of nomenclature support the priority of cassinii (Article 33.4). The correct spelling for the 13-year relative is tredecassini.
- Fisher, J. C. 1852. On a new species of Cicada. Proceedings of the Academy of Natural Sciences of Philadelphia 5: 272-275.
- Sanborn, A. F. 2013. Catalogue of the Cicadoidea (Hemiptera: Auchenorrhyncha). With contributions to the bibliography by Martin H. Villet. Elsevier. Inc., Academic Press, San Diego, CA.
- Duffels, J.P., and P. A. van der Laan. 1984. Catalogue of the Cicadoidea (Homoptera, Auchenorhyncha) 1956-1980. Series Entomologica vol. 34. 414 pp. Junk, Dordrecht, Netherlands
- Metcalf, Z.P., 1963. General Catalogue of the Homoptera. Fasc. 8. Cicadoidea. Part 1: Cicadidae. vii, 919 pages. Part 2: vi, 492 pages. [Species index by Virginia Wade, 1964, 26 pp.] University of North Carolina State College, Raleigh, U.S.A.
- Dmitriev, D. 2003. 3I Interactive Keys and Taxonomic Databases.
- ICZN, 1999. International Code of Zoological Nomenclature, 4th Edition Archived 2009-05-24 at the Wayback Machine. International Trust for Zoological Nomenclature, Natural History Museum, London.
- Alexander, R.D., and T. E. Moore. 1962. The evolutionary relationships of 17-year and 13-year cicadas, and three new species (Homoptera, Cicadidae, Magicicada). Miscellaneous Publications of the Museum of Zoology of the University of Michigan 121: 1-59.
- "Periodical Cicada Page". University of Connecticut. Retrieved 14 May 2018.
- Carter, Janet L. Stein. "Periodical Cicadas". University of Cincinnati. Archived from the original on 2011-07-28. 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. Archived from the original (PDF) on 7 August 2011. Retrieved 18 June 2011.