The Mississippi Valley Brood
Brood XXIII contains the species Magicicada neotredecim, Magicicada tredecim, Magicicada tredecassini, and Magicicada tredecula though only populations in the contact zone contain all four species. Brood XXIII has a small disjunct in Weldon Springs State Park, DeWitt County, IL.
In the map below, cicada symbols are verified presence records and red crosses are verified absence records in our database as of January 2024. 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. Symbols are in layered in the order Database, Simon, Marlatt, 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, found in five separate broods, some of which include disjunct populations.
Stannard (1975) published a map of all Illinois periodical cicada broods. Brood XXIII has a small northern disjunct in DeWitt County; Stannard attributed these populations to 17-year Brood III, but they clearly belong to Brood XXIII instead.
In the map below, cicada symbols are verified records in our database as of February 2021. Closed circles are records of the brood from Stannard (1975); open circles represent absences of the brood. The shaded area represents Stannard’s estimation of the brood boundary. This map may not be reproduced without written permission.
Reproductive Character Displacement
The pattern of reproductive character displacement (RCD) between Magicicada neotredecim and M. tredecim is less pronounced in Brood XXIII than in Brood XIX, because few populations of Magicicada neotredecim are found in the absence of M. tredecim.
Generally, where M. neotredecim and M. tredecim overlap, they exhibit a pattern of reproductive character displacement in calling song pitch and female pitch preferences. Within the zone of displacement, the dominant male call pitch of M. neotredecim is 1.7 kHz, while outside the contact zone, its call pitch is ca. 1.4 kHz, identical to that of its putative ancestor, M. septendecim.
