Only once every 221 years: billions of cicadas from two groups with different life cycles crawl out of American soil at the same time this year

They look a bit like grasshoppers, but the insect genus Magicicada belongs to the cicada group. They only live in the eastern US and have a special life cycle of 13 years or 17 years. These two cycles coincide every 221 years. Then these cicadas all crawl out of the ground by the billions. This year it’s that time again. So the last time was in 1803.

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