The Great Southern Brood
Brood XIX is arguably the largest (by geographic extent) of all periodical cicada broods, with records along the east coast from Maryland to Georgia and in the Midwest from Iowa to Oklahoma. Although 13- year cicadas are generally considered to have a southern distribution, the northernmost known record of this brood is in Chebanse, IL, roughly 75 miles from Chicago’s Loop. This brood includes the species Magicicada neotredecim, Magicicada tredecim, Magicicada tredecassini, and Magicicada tredecula although only populations in the contact zone contain all four species.
In the map below, cicada symbols are verified presence records and red symbols are verified absence records in our database as of March 2025. Click on points for details. Gold symbols are from Simon (1988); smaller symbols are records with a lower degree of certainty and black crosses represent records that are considered spurious. Blue symbols are from Marlatt (1923); smaller symbols are records with a lower degree of certainty and question marks represent records that are considered spurious. Purple symbols and shading represent Stannard’s (1975) delineation of the brood in Illinois. Areas that Stannard incorrectly attributed to Brood III are also included as green symbols and shading. Symbols are in layered in the order Database, Simon, Marlatt, Stannard and symbols in the upper layers may obscure symbols in lower layers. Some absence records in the database are not shown for clarity. Note that the dates shown do not represent dates of adult emergence; rather, they represent dates on which choruses were active. Thus, in any given area, adult emergence may have occurred a week or more earlier than the dates shown on this map. This map may not be reproduced without written permission.
Illinois presents a particular challenge for understanding periodical cicada biology, because it contains both 13 and 17 year life cycles, all 7 currently recognized species, and five separate broods, some of which include disjunct populations.
Stannard (1975) published a map of all Illinois periodical cicada broods. Stannard’s map of Brood XIX includes a small northern disjunct that is instead a part of Brood III, and his delineation of the brood boundary in Adams, Brown, Hancock, and Schuyler includes areas that are also part of Brood III. Â In DeWitt County Stannard attributed populations to 17-year Brood III, but they belong to Broods XIX and XXIII instead.
Reproductive Character Displacement
An interesting feature of Broods XIX and XXIII is a striking pattern of reproductive character displacement (RCD). Where Magicicada neotredecim is in contact with another 13-year species, M. tredecim, the dominant male call pitch of M. neotredecim is approximately 1.7 kHz, while outside the contact zone, its call pitch is approximately 1.4 kHz, identical to that of its putative ancestor, M. septendecim; female pitch preferences match (Marshall and Cooley 2000).
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