Why There Are No Cicadas In Your Backyard


Why aren't they at your house? It's not you, it's them. Well, it's also you. - IMAGE VIA
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  • Why aren't they at your house? It's not you, it's them. Well, it's also you.
STL has gone cuh-razy for cicadas, now that the 13-year periodical brood has come out in force. But this big ol' cicada party ain't raging everywhere -- only in certain pockets. What gives?

It's actually a question of human behavior, as well as cicada preference, says Rob Lawrence, Ph.D, a forest entomologist at the Missouri Department of Conservation.

The Human Factor

"Human activity has a lot to do with it," says Dr. Lawrence.

When people knock down trees for subdivisions or commercial development, they wreak havoc on the cicada life cycle.

Cicadas lay their eggs on tree branches. After hatching, the little nymphs drop down to the soil and burrow underground, where they feed on plant roots for thirteen years. Tear up that habitat with a bulldozer, and those little guys are history.

But wait, you say: Your neighborhood was developed a long time ago. Well...how long ago? These periodical cicadas only come out for a couple months every thirteen years, and they don't travel very far once they do. So what did your neighborhood look like three cicada generations ago (meaning about 40 years ago)? Were there enough mature trees at the time for them to lay their eggs?

What Cicadas Like to Do

For one thing, cicadas don't spread out rapidly because (as mentioned above) they don't come out very often.

"They do fly around a lot," Lawrence says, "but the males like to congregate in 'chorusing centers,'" whereby they sing together to attract the maximum number of females from the farthest distance possible (also known as the NKOTBSB approach).

"So you get clumping from their own behavior and clumping from changes to tree cover," Lawrence concludes, adding: "There's probably other reasons, too, we don't understand yet."

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