Cicada researcher: Bring an umbrella under trees
Katie Roupe/Observer-Reporter
The cicadas are emerging in Washington County, and researcher Kelly Hougland took the opportunity to analyze what makes cicadas emerge from the ground in 2016.
Kelly Hougland, a doctoral candidate at University of Missouri-Columbia, discusses his ongoing research project into cicadas and whether they use social cues to emerge from the ground. Hougland has a section set up at Abernathy Field Station in partnership with Washington & Jefferson College to document sounds and photos from when the cicadas are in the ground until they emerge.
One of the most fascinating cicada behaviors can be observed in one of the four species in the Brood V group that’s emerging for the next two weeks. The magicicada cassini (cass-uh-nye) can make a tree look like it’s indeed something out of a fairy tale.
“This species makes a click noise before their mating call – that whirring sound – and they’ll move en masse if they don’t get a response. So if they click, call and don’t hear any females clicking back, they’ll all fly away from a tree all at once. It’s almost like seeing the tree breathe away the cicadas. It’s very cool,” said Kelly Hougland, a researcher and doctoral candidate with the University of Missouri studying cicada emergence at Abernathy Field Station in Amwell Township, in partnership with Washington & Jefferson College.
That collective Marco Polo mating call is partly why Hougland has a hunch that the mud bugs are doing more than simply sapping away nutrients from trees during their 17 years underground.
The 33-year-old St. Louis native has set up cameras and underground sound-detection devices to gather data on whether cicadas communicate before emergence. In other words, do they “chat” about the weather before collectively deciding to burrow out from the ground?
“The current literature focuses on soil temperature. I’m looking at how they decide and when they come out of the ground. Since temperature is understood as the primary motivator for when they come up – once the soil gets warm enough – there must be something else going on, because there are shady spots, rocks and other factors that prevent perception of true surface soil temperature,” Hougland said.
Hougland’s lab at the University of Missouri focuses on treehoppers, to which cicadas are a close cousin. Their diverse social interactions gave Hougland the hunch cicadas might engage in similar collaborative, collective-intelligence behavior. “Treehoppers will make big, macro decisions on feeding. Once they vote, of sorts, and decide a threshold has been met that there’s no more food available, they’ll move all at once – like the cicada mating calls as adults,” Hougland said.
To account for other variables, Hougland set up “isolation pots” with cicada nymphs he dug out of the ground. It could be anything from a mole to a cricket contributing to the cacophony of underground noise, so he’ll isolate sound frequencies made by nymphs to help clear up what sounds are actually made by them.
“The accelerometers will measure variances in soil disturbance … (and) the trail camera will record time-lapse pictures of when they emerge,” he said.
Once they get above ground, they’ll soon start feeding and calling after about a week. Then, another phenomenon, known jokingly by biologists as “cicada rain,” starts happening.
“Cicadas feed on the xylem of trees, which is almost entirely water, with a few hormones and minerals. So they take on more water than they need. They’re excreting that excess water constantly. So if you’re standing under a tree and it feels like it’s raining, that’s them peeing. Bring an umbrella,” Hougland said.
While residents in Maryland, West Virginia and Southwestern Pennsylvania will deal with the flying arthropods in 2016, Allegheny County bug fans have to wait until 2019 for the emergence of Brood VII. But their appearance in Southwestern Pennsylvania has benefits.
“They’re a huge, free protein source for predators, so you’ll see the size and population of animals booming; tree growth because the egg-laying process is a natural pruning of tree limbs; and it’s great for the soil. When they die, they’ll provide fertilizer for the soil, and their burrowed holes aerate the soil,” Hougland said.
For Hougland, studying them is a personal quest.
“Studying bugs, and especially collective behavior and intelligence, it helps us as scientists understand large and complex systems. We’ll better understand ecosystems,” Hougland said.