Two broods of the insect are appearing simultaneously for the first time in 200 years in North America
In April 2024, trillions of periodical insects descended on the Midwest and Southeast of the United States, causing so much noise that local residents called the police to complain. These insects were cicadas.
Two broods of cicadas, Brood XIX and Brood XIII—which emerge every 13 years and 17 years, respectively — are appearing simultaneously for the first time in 200 years.
There are more than 3,390 species of cicadas worldwide, but only seven in North America are known to be periodical.
The rest emerge annually. Periodical cicadas live several inches underground, feeding on sap from plant roots. When the soil temperature reaches about 18 degrees Celsius (64 degrees Fahrenheit), they emerge.
Cicadas do not bite, sting, or carry diseases and cannot be effectively controlled with pesticides.
Male cicadas produce a loud buzzing sound by singing together from the trees to attract females. Interested females respond with a quick flick of their wings, producing a more subtle clicking sound.
Cicadas not only disrupt neighbourhoods with their deafening noise, but they can also cause chaos in food chains. While the insect outbreak will be brief, its effects on forests could be long-lasting.
The insects provide a lavish feast for all kinds of wildlife, especially birds and small mammals. Birds of all shapes and sizes—such as sparrows, crows, and swallows—shift their diets to take advantage of this cicada banquet.
A study published in 2023 found that the emergence of periodical cicadas changes the diets of entire bird communities, with these effects rippling throughout the ecosystem.
Although cicadas can be harmful to young trees, as females lay their eggs in new tree growth, they can also be beneficial to the region's ecology. They aerate the soil as they create emergence holes, improving water infiltration and encouraging root growth. When they die and decompose, they add nutrients to the soil.
However, relatively little is known about the real-time effects of living cicadas on food webs. Scientists are capitalising on this year's dual emergence to learn more about the ripple effects these insects have on other species in both the animal and plant kingdoms.
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