Cicadas: The loudest insects you've never seen

· The Pulse

Cicadas help create the buzzing soundscape of the city on hot summer nights, but the insects themselves are a rare sight.

"I think I've only actually seen one in Edmonton. They like to go high up into trees, and they're really tough to get a hold of," said Ferf Brownoff, a self-described amateur cicada enthusiast, confirming the experience of a curious Taproot reader.

Unlike their impossible-to-ignore periodic cousins in the eastern U.S., which emerge in gigantic broods in 13- or 17-year cycles, the seven species of cicada in Alberta are annual varieties that have some nymphs reaching maturity every season. This makes them a more consistent part of our environment, but one whose limited numbers could easily be invisible in the landscape if not for their piercing calls.

"They sound like an oppressively hot day," said Brownoff, an undergrad in the conservation biology program at the University of Alberta. "I can hear them all the time on a nice, sunny, hot day. And typically, that's the only times that I do hear them."

Male cicadas produce their characteristic sound with a specialized organ called a tymbal. These membranes are found on the insect's abdomen and elicit a sharp click when they contract and relax. Buckling between 300 and 400 times per second, the tymbal's percussive noise sounds continuous to the human ear.

More than having just a sonic association with summer heat, the cicada's life cycle is precisely linked with temperature. Nymphs stay in the soil, feeding on sap from tree roots until the thermometer hits about 18 C.

"That's kind of a signal that tells them, 'Now it's OK. This is the time that you can come up from the ground, and then turn into your adult stage,'" Brownoff explained. Along with temperature, humidity has been associated with successful adult cicada populations, Brownoff said, making this year's muggy July an ideal time for them to shed their skin and join the raucous party in the treetops of the river valley.

Some form of cicada has existed on this planet since the Late Triassic, and they can be found on every continent except Antarctica. It was while living in Japan that Brownoff first noticed the insects dangling from tree branches, triggering his enduring fascination.

A large winged insect sits in the palm of a man's hand

Conservation biology student Ferf Brownoff managed to catch a cicada in Waterton earlier this month. In Edmonton, they're more often heard than seen. (Supplied)

"One of the first things I experienced when I moved to Japan was a cicada emerging from its nymphal stage on a tree. I thought it was the wildest looking thing," Brownoff recounted. "I often tell friends, this is a silly thing, but if you got every video game designer or Disney and Pixar designer in the world together in a room to design something, I do not think they could do a better job than what a cicada looks like."

Grasshoppers, crickets, and katydids are the other main species of singing insects, all of which can be found throughout Alberta. As climate change shifts habitable zones further north, scientists are also hearing unfamiliar songs of invasive species in the region. Originally from Europe, the non-native Roesel's katydid has been spotted in the Edmonton area in recent years, or rather their unique stridulations have announced their presence. One research project from MacEwan University sought to use field recordings to identify their songs and map their advance into the province.

These intruding species have caught the attention of researchers, and grasshoppers have long been the focus of study because of their potentially catastrophic economic impact (even a small infestation can consume 60% of available foliage). But Canadian cicadas, despite being the loudest of the insect chorus, have largely evaded the penetrating gaze of scientists.

In an exchange with Gene Kritsky, known as the No. 1 cicada guy in the U.S., Brownoff asked about opportunities to study cicadas and was reminded of how much still needs to be explored in our own backyard. "He said you could study Canadian cicadas because there's so much unknown there. And even he was seemingly at a loss as to why that is," Brownoff recalled.

"Perhaps it's because they're just so hard to come across ... They're not a pest species that is destroying people's gardens or farmer's crops. They're just there in the background."

Because cicadas aren't closely monitored, it's hard to say whether they are indeed more plentiful this year. It seems plausible, given that this humid summer is an ideal climate for cicadas, but for the time being, you will have to spend a hot summer evening among the trees and let your ears be the judge.