Cicadas go through an extraordinary life cycle. There are two types: annual and periodical. While annual cicadas show up every year, it's the periodical ones that are truly fascinating.
Periodical cicadas spend most of their lives underground as nymphs, only to emerge simultaneously across large areas after 13 or 17 years. This long phase, spent beneath the soil, is a growth period during which the nymphs feed on sap from tree roots.
The emergence of cicadas is a natural spectacle that changes the landscape. Male cicadas climb onto tree branches to sing together, creating a loud chorus to attract mates. After mating, female cicadas lay their eggs in tree branches. When the eggs hatch, the new nymphs fall to the ground and burrow into the soil, beginning the cycle again. Tree branches The combination of the spectacular cicada emergence and the lengthy waiting period makes a cicada spawning season significant in the eastern and midwestern United States. This year is special because both a 13-year brood and a 17-year brood will emerge at the same time. A “brood” is a scientific term for a group of cicadas that emerge simultaneously.
Sometime around mid-May, a massive number of cicadas will descend, especially upon Illinois. This is the first time since 1803 that two broods will emerge at the same time. The next double cicada event won’t happen until 2037.
The unique event of both a 13-year brood and a 17-year brood emerging simultaneously will take place around mid-May this year, bringing a huge number of cicadas, particularly to Illinois. This is the first time since 1803 that two broods will emerge at the same time. The next occurrence won’t happen until 2037.
The occurrence of two broods emerging simultaneously has not happened in over 200 years. The next double-cicada event won't take place until 2037.
Map of dual cicada brood emerging in 2024. Source: The Cidada Project at the University of Connecticut/The Washington Post.
Broods are classified based on their geographical location and the timing of their emergence, each assigned a unique Roman numeral for identification. There are 15 identified broods of periodical cicadas in the United States. 12 of these are 17-year cicadas and 3 are 13-year cicadas.
These broods emerge in different years and geographical locations, often covering specific areas in the eastern and central United States. Over time, scientists and nature enthusiasts have thoroughly mapped the location and cycles of each brood, allowing them to predict when and where an emergence will occur.
This spring and early summer, Brood XIX (known as the Great Southern Brood) will appear in several states including Missouri, Arkansas, southern Illinois, Tennessee, Alabama, Georgia, the Carolinas, and surrounding states after hibernating for 13 years. Brood XIII, or the Northern Illinois Brood, will emerge from its 17-year cycle in Illinois, Iowa, and Wisconsin. The next occurrence of both of these breeds emerging simultaneously won't happen for another 221 years.
The exact timing of when this will happen is not known. Once the insects are fully grown and the nearby soil reaches 64 degrees Fahrenheit (17 degrees Celsius), the cicadas are ready to go.
The area where the two groups of cicadas overlap is not very large, which could be a good thing given the disturbance this may cause. Scientists are especially excited