How cicada researchers use data to track and document the Brood XIX and Brood XIII cicada emergence

2024 is a big year for researchers who study periodical cicadas known as Magicicada. Two broods of Magicicada, Brood XIX (19) and Brood XIII (13), will both emerge for the first time in 221 years. Brood XIX has a 13-year life cycle and Brood XIII has a 17-year life cycle; 17 times 13 equals 221. Their territories do not overlap, though they come very close near Springfield, Illinois. Brood XIX is found in the states of Alabama, Arkansas, Georgia, Illinois, Indiana, Kentucky, Louisiana, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, and Virginia. Brood XIII is found in Iowa, Wisconsin, Illinois, Indiana, and possibly Michigan.

Cicadas with precise and predictable periodical life cycles are rare. There are only two other types of known periodical cicadas: Chremistica ribhoi, a cicada found in India, which has a 4-year life cycle that occurs the same year as the men's World Cup, and Raiateana knowlesi a cicada found in Fiji, which has an 8-year life cycle. Cicadas that have periodical life cycles tend to emerge in massive numbers. Waking up to thousands of newly emerged, red-eyed cicadas crawling around your suburban yard can come as quite a shock. Days later when they start singing it is even more shocking! More surprising than an eclipse because they'll be around for four weeks, not a single day.

There are twelve broods of Magicicada with 17-year life cycles (1-10,13,14) featuring three unique species, and three with 13-year life cycles (19,22,23) featuring as many as four unique species. No two 17-year Broods can emerge in the same year, and no two 13-year Broods can emerge in the same year, but 17 and 13-year broods do co-emerge. Two broods have gone extinct: XXI (21), once found in Florida, but not since 1870, and XI(11), once found in Connecticut, but not since 1954. Both likely died off due to pressures from the destruction of their habitats.

Mapping the location of the broods has been a passion for cicada researchers since the 19th century. Entomologist Charles Lester Marlatt, who established the Roman numeral brood naming convention, spent his springs surveying the eastern United States on horseback. Back in the late 19th century and early 20th century data collection was powered by horse, mail, and telegraph. Marlatt would manually compile his observations with communications from colleagues and plot the locations of cicadas on what is called brood maps.

The collection of cicada data and the creation of brood maps is much easier in the 21st century, but no less fun, interesting, and important.

The main sources of Magicicada data are:

1. Historical knowledge is collected and entered into modern databases. This knowledge includes Marlatt's brood maps and information collected from newspapers, letters, and other documents dating back as far as the 18th century. One of the original periodical cicada databases was created by Chris Simon and made available on the web on the University of Connecticut website (https://hydrodictyon.eeb.uconn.edu/projects/cicada/databases/magicicada/magi_search.php).
2. Cicada researchers travel the United States by car and use “cicada track o matic” PC + GPS devices to document the location of the individual species of cicadas and their density. This method is useful for exploring the boundaries of broods and places with low population densities, where data from citizens is difficult to come by. John Cooley from the University of Connecticut devised the "Cicada Track-o-Matic", funded by the National Geographic Society Committee on Research and Exploration. Learn more about this research here: https://cooley.eeb.uconn.edu/research/.
3. Gathering data from the Cicada Safari App (https://cicadasafari.org), which uses photos and geographic data posted by citizen scientists. This app is available for iOS and Android devices and is produced by Gene Kritsky and Mount St. Joseph University.
4. Gathering data from iNaturalist (https://www.inaturalist.org), which is a website and app that allows anyone to get AI-assisted identifications of their photos of animals, fungi, and plants. Cicada researcher Jesse Smith curates the 2024 Magicicada: Broods XIII and XIX project (https://www.inaturalist.org/projects/2024-magicicada-broods-xiii-and-xix) on iNaturalist and assists naturalists with manually verifying the species found in the photos they upload.

Researchers John Cooley, Gene Kritsky, and others compile the data and build official brood maps which you can find on cicadas.uconn.com at https://cicadas.uconn.edu/broods/. They can also determine important information including how much the broods are geographically expanding or shrinking (mostly shrinking). Human behavior places a heavy burden on all types of wildlife. Unfortunately with cicadas, we can only observe the impact of human behavior every 13 to 17 years, which makes collecting data about their locations all the more important.

If you are interested in helping track cicadas, download the Cicada Safari app and get an iNaturalist account. I highly encourage you to do so! Cicadas exist on every continent except for Antarctica, so if you're not in a location where periodical cicadas exist, there are plenty of other types of cicadas you can find and report.

As a citizen scientist, and owner of www.cicadamania.com, my research was included in five papers about cicadas (https://scholar.google.com/citations?view_op=list_works&hl=en&user=2nqv7aAAAAAJ). I recently used iNaturalist data (which anyone can download from the site) to determine when Platypedia cicadas will emerge in northern Utah (https://www.cicadamania.com/cicadas/guessing-at-when-the-next-platypedia-or-okanagana-hatch-will-happen/) which is of great interest to fly fishers.