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.
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
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
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.
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
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."
STL has gone