Rare Event: Two Cicada Broods Emerge Together For First Time in 221 Years




In the enigmatic world of periodical cicadas, this year is unique because it is the first time since 1803, when two distinct broods have simultaneously emerged in the United States.

Periodical cicadas (Magicicada spp.), one of the biggest mysteries of the insect kingdom, spend up to 99.5 percent of their lives underground as nymphs, where they feed on the sap of tree roots. A brood may take 13 years or 17 years to reach adulthood.

These two broods' simultaneous emergence in 2024 represents a unique instance of their 13- and 17-year life cycles coordinating. There won't be another great double event like this until 2245.

When they mature from wingless nymphs to adults, millions of cicadas from Broods XIII and XIX will emerge from the ground around mid-year to shed their exoskeletons, leaving behind husks that may cover trees and other surfaces.

After then, the adult cicada's existence consists solely of mating and laying eggs.


Although the sheer volume of cicadas singing at up to 90 dB can be rather annoying, cicadas do not pose a threat to people or animals.

The surprisingly loud commotion is produced by the males, who use their tymbals, vibrating structures on the sides of their abdomens, to compose species-specific mating songs that entice the mute females.

Following mating, females create holes in tiny tree branches using a tool known as an ovipositor, which they use to deposit their valuable egg cargo. In a matter of weeks, the mature cicadas will marry, lay eggs, and eventually perish.

Following hatching, the eggs become nymphs, who spend almost their entire lives underground as they dig into the ground and start the next 13 or 17 year cycle.


The exact timing of the cicadas' mass arrival into the above-ground world is unknown, but new developments indicate that the enigma of the Magicicada may be resolved in the next ten years.

It is believed that the large number of these inquisitive creatures during their synchronized emergence serves as a protection against predators including birds, wasps, and mantises. The likelihood that cicadas will elude predators and find a mate is undoubtedly increased when the ecosystem is overrun with more of them than can potentially be eaten at one time.

By taking advantage of this and matching their life cycle with the cicadas' to guarantee an abundance of food during mating season, predators may grow more dangerous and maybe stop any cicadas from escaping their inevitable end as food.

However, it seems that periodical cicadas' lengthy life cycles assist prevent predators from timing their mating seasons. They may also evade predators whose life cycle depends on prime numbers (such as 13 and 17) since they have a seasonal breeding cycle based on those numbers.

For example, a 12-year cicada species might be wiped out by any predator species with a life cycle of 2, 3, 4, or 6 years, as each emergence of a new cicada species would result in an increase in the predator population.

A 'brood' is made up of all periodic cicadas with the same life cycle type and emergence year.

Investigating these broods can yield important information on population dynamics, insect behavior, and the effects of cicada emergence on the environment. Among the insects with the greatest research on their ecology and evolution are magicicadas.

This is the only mammal with a life cycle this long, steady, and coordinated, reproducing both several times and in vast numbers. However, one fascinating arthropod approaches really closely: the Japanese millipede, whose population grows every eight years.




The Northern Illinois Brood, or Brood XIII, was last observed in 2007. This brood inhabits the eastern United States and emerges every 17 years. They will likely be heard buzzing across Wisconsin, as well as certain areas of Illinois and Indiana.

The southeastern US is the primary habitat of Brood XIX, often known as the Great Southern Brood, which was last observed in 2011. This 13-year cycle brood will appear in Tennessee, Georgia, Texas, Alabama, and other places.

Although the exact date of their appearance may change slightly according on the weather, broods XIII and XIX are anticipated to surface between May and June, when soil temperatures will have reached around 17.9 °C (64 °F).

There is a major geographic overlap in Illinois, where you may hear the mixed songs of both broods along with some other regions.

Magicicadas may be found anywhere, including in parks, urban areas, and even your garden.