An upcoming cicada apocalypse in the U.S. is expected to be a rare and unique event in the animal kingdom. Millions of cicadas will emerge and two broods will come out at the same time, the latter of which has not happened for more than two centuries. In fact, the last time this kind of event occurred was in 1803.
How will that affect us? Cicadas are harmless to humans. However, we’re talking about millions (or trillions) of insects with a very particular noise that can be quite annoying. That loud buzzing or “singing” noise can reach up to 90 decibels, which is equivalent to the sound of a jackhammer up close. Exposure to this noise for as little as 15 minutes can even cause hearing loss, according to the Centers for Disease Control and Prevention, or CDC.
Why is this an extraordinary phenomenon? First, it involves periodical cicadas (magicicada spp). These insects reproduce based on a prime number, specifically every 13 or 17 years, which makes them a fascinating enigma. Secondly, millions of offspring from two different broods, XIII and XIX, will emerge from the ground at the same time between May and June. It's quite amazing.
The phenomenon last occurred in 1803 and is not expected to happen again until 2245. The event is exclusive to the U.S., where the species originated. The XIX generation will appear predominantly in the Southern states, while the XIII generation will come out in a small section of the Midwest, primarily Illinois.
What is it about prime numbers? Scientists have no conclusive evidence to explain why this occurs, but it does. Some believe that cicadas are able to track the seasons and detect the flow of sap in trees to determine the number of years that have passed.
Others suggest that cicadas emerge in large numbers to protect themselves from predators such as birds, wasps, and mantises. By flooding the ecosystem with more cicadas than predators can consume, they increase their chances of survival and finding mates. Additionally, the long cycles of periodic cicadas may help prevent predators from synchronizing with their breeding times.
Periodic cicada locations in the U.S. and when they’re expected to emerge.
And what will happen when the cicadas emerge? Something equally extraordinary. Cicadas spend 99% of their lives as underground nymphs, protecting themselves, tunneling, and feeding on the sap in tree roots. The subterranean world is cold, so they stay still until it’s time to emerge. Some hatchlings take 13 years to become adults. In other cases, they can take up to 17 years to reach maturity.
Cicadas emerge in late spring when the soil temperature reaches an optimal level. However, the time of their emergence varies between late April and early June depending on the location and temperature. For instance, the XIII generation may appear between late May and early June, while the XIX generation, also known as the Great Southern Brood, may emerge at the end of April.
Cicada molting: from nymph to adult.
Metamorphosis and molting. Once they're outside, cicadas move on to the next phase of their life cycle. The males usually emerge first, or within the first few days, and climb trees to wait for the females to follow suit. During this time, they shed their old exoskeletons and develop new ones to become fully grown adults.
In rural areas, especially those near rivers, people might shovel the discarded exoskeletons into buckets (and even fill them to total capacity) at this stage. Once the transformation is complete, the insects begin their courtship rituals.
Mating. Male cicadas use an organ in their body to produce a humming sound that can reach up to 90 decibels. This "song" is what people recognize. When a female responds to the call, they mate. The female then searches for brighter areas and locates tiny branches where she uses a special organ called an ovipositor to cut holes and lay up to 600 eggs.
If there’s no more room on one branch, female cicadas fly to another and repeat the process. Once the mission is complete, adult cicadas usually die in short succession. About six weeks later, the eggs hatch from the trees, fall to the ground and bury themselves to start the cycle again. It’s important to remember that this cycle occurs every 13 or 17 years.
Will the cicadas emerge outside the U.S.? No, they won’t. This means that Mexico and any other nearby country will be safe from this cicada apocalypse, which some have termed the “cicada-geddon.” In any case, they’re harmless. As we mentioned earlier, these insects are native to the U.S. and only emerge here, which is understandable considering their strict and accurate life cycle.
Image | Jeff Herge | Mike Lewinski| Andrew M. Liebhold, Michael J. Bohne, Rebecca L. Lilja | Public domain
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