Trillions of red-eyed cicadas are about to emerge from underground and sing loud songs. The creatures can seem downright creepy, but they’re not monsters or a plague of locusts. Scientists say that once you get to know them, you can appreciate them. Why are there so many this year? It’s an evolutionary defense mechanism for a creature that lots of other creatures want to eat. They come out in large numbers so that some of them will survive, and scientists say the survivors make up the next brood. For this group of bugs, those survivors will emerge again in 17 years.
