There are more than 3,390 species of cicadas around the world, but only seven in North America are known to be periodical. The rest emerge annually. Although they are classed as distinct species, many species of periodical cicadas are able to interbreed, producing hybrids.
It means that where the broods cross over this year, three species of Brood XIII cicadas will have the opportunity to interbreed with four species of Brood XIX cicadas, Raupp explains. “The outcome of this will produce hybrids and only the cicadas and Mother Nature know what the outcome will be,” he says.
When periodical cicadas emerge, they bring great benefits to the environment where they live. The nymphs aerate the soil as they tunnel to the surface, improving water infiltration to the ground and encouraging root growth. When they die and decompose, they add nutrients to the soil.
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But like most other creatures, cicadas’ behaviours are changing. They are emerging earlier in the spring than they did a century ago, says Kristky. “And there have been more broods emerging four years ahead of schedule.” Destruction of forests threatens populations too – in 1954 the entirety of Brood XI went extinct, due to forest clearing to make way for agriculture and urbanisation.
What draws entomologists like Raupp and Kritsky back is the mystery of the bugs – and the fact that it’s nature putting on a show. “There could be more noise, more fear for entomophobes, more fun for bug geeks like me,” says Raupp. “And yes, it is a wicked cool and interesting event that happens nowhere else on Earth.”
The next time Broods XIX and XII emerge together it will be 2245. The question is: what kind of world will they be coming out to?
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