It is important to note that when we talk about cicada broods, we are talking about the 17 & 13 year periodical Magicicada cicadas. We are not talking about Tibicen or other species.
There are 12 groups of Magicicadas with 17 year life cycles, and 3 groups of Magicicadas with 13 year life cycles. Each of these groups emerge in a specific series of years, rarely overlapping (17 & 13 year groups co-emerge every 221 years, for example). Each of these groups emerge in the same geographic area their parents emerged. These groups, each assigned a specific Roman numeral, are called broods.
Gene Kritsky’s book, Periodical Cicadas: The Plague and the Puzzle, documents the history of the recognition and naming of the broods. The first person to document that different groups of periodical cicadas emerged in different years was Nathaniel Potter in 1839. Benjamin D. Walsh and Charles V. Riley devised the system for numbering the different broods in 1868, and then C. L. Marlatt sorted the 17 year broods out from the 13 year broods, giving us the system we have today.
Visit our Broods page which features a grid of the Brood names, their life span, when & where they’ll emerge next and links to maps.