TERRE HAUTE, Ind. (WTHI) - It's something that happens every year, and it happens so often you've probably taken notice.
"From my records, the annual cicadas that we've heard this year came out exactly the same day as last year, at least from my own personal records."
Dr. Peter Coppinger is a professor of biology at Rose Hulman.
He says cicadas come out every summer, but there are a few different kinds we see.
"Right now, the cicadas that we're hearing are the annual cicadas. These are cicadas that come out every single ear. They have a lifespan of about two to five years, and that is different from the periodical cicadas, the cicadas that come out every thirteen years, or seventeen years."
But Coppinger says there really isn't a set date on when they come out, and some people see more of them than others.
"The timing of their emergence kind of overlaps with each other, so you might see in some areas more cicadas than others, and those are kind of these different, separate populations emerging at different times."
So, what are their differences?
"The dog day cicada, the cicada we hear now is much bigger. It's got these green and brown markings, whereas the periodical cicada is black, much smaller, and when it's alive, it has red eyes."
Coppinger says the good news is, they are relatively harmless to humans, although some of them can do some damage to the environment.
"Those periodical cicadas, those cicadas that come out every seventeen years, they really can do some damage to trees, usually younger trees. But the annual cicadas around here this time of year, you might not really notice any damage at all."
So your best bet is to let them be and enjoy the peaceful sounds they make on warm summer nights.