The department of biology at North Carolina State University is looking for crooked cicadas: cicadas with one wing slightly shorter than the other, or with a wing containing an odd number of veins, or maybe a little leg segment that's not quite the right length. The scientific term for these quirks is "fluctuating asymmetry." But, for simplicity's sake, Holly Menninger is just calling it "crookedness."
You may be familiar with the allure of symmetry in nature. Supposedly, we're programmed as humans to find beauty in the most mathematically symmetrical faces.
"But there’s this other notion about how the lack of symmetry may be an indication of environmental stress, that environmental stress may somehow in subtle ways affect the process of development, particularly of insects," says Menninger, the director of public science for the university's citizen-science Your Wild Life Program. "We don’t know exactly what the mechanism is that causes those differences of symmetry. We just know that that's how the body plan responds to stress."
If the cicadas now emerging on the East Coast from Brood II exhibit some of these idiosyncrasies, that may tell scientists something about the role of urbanization in cicada habitats. Last week, we wrote about the terrible time these insects have surviving in the face of massive development projects. Cicadas live off of trees. And so when we rip out trees to build parking lots or subdivisions, we inadvertently wind up killing cicadas, too.
It's possible, though, that urbanization may have some subtler impacts on cicadas, too, as the pollution from our cities or the heat generated by them influences the development of the insects that do survive.
"We don't really know enough about what those stressors are," Menninger says. "This measure of asymmetry is the first step to determining that something might be going wrong."
The project is asking for dead cicadas wherever you may find them – in an urban neighborhood, in the country, hopefully thousands of them up and down the entire Brood II range. Researchers will later compare the exact locations of the found cicadas with local measures of urbanization such as land cover data from satellites. In the end, they'd like to learn if this degree of "crookedness" correlates with the degree of urbanization.
So how do you ship a dead cicada if you've got some in your back yard? They're pretty hearty insects, Menninger says. She suggests mailing them in a take-out container lined with tissue paper.
"We’ve been very specific that we want dead ones," she says, "because we want to give these creatures an opportunity to fulfill their reproductive potential. It would be pretty mean if they came up from the ground and we immediately popped them in the freezer and didn’t give them a chance to mate."
She does suggest, however, that you put your dead cicadas in the freezer overnight before mailing them. Other insects like ants may have already started digging in. "We don’t want the hitchhikers," Menninger says, "to come along with them."