Hellbender Press - The sounds of silence: 17-year cicadas fade away as offspring prepare for 2038 performance

Wednesday, 30 June 2021 17:58

The sounds of silence: 17-year cicadas fade away as offspring prepare for 2038 performance

Written by Stephen Lyn Bales

font size decrease font size increase font size
Email

Dead cicadas are seen on concrete in Knoxville at Holston River Park. Their brief sonic reign has come to an end. Photo courtesy of Lyn Bales

The cicada soundtrack of spring and early summer has come to a quiet end

“Turn out the lights, the party’s over,” sings country music outlaw Willie Nelson. “They say that all good things must end.”

Yes. Essentially Cicadapalooza 2021 is over. There may be a few late emerging males hanging on like the last few guys in the bar at closing time with hope against hope that somehow they will get lucky and Miss Wonderful will walk through the door. In this case, a female 17-year cicada clicks and clicks to let the male know she is interested or desperate to complete her mission.

As a rule of thumb, the entire periodical cicada phenomenon lasts four to six weeks but it is extremely weather dependent. Insects are ectothermic and need warm to hot temperatures to be active.

I saw my first evidence the cicada emergence had begun at Ijams Nature Center, where I worked for 20 years as a naturalist. Executive director Amber Parker told me where to look for emergence holes: under the sugar maple at the back of the Universal Trail. That was on April 20. I found the small exit tunnels but no cicadas or exuviae. I knew skunks, foxes, crows, jays, owls, dogs, cats, and anything else that will eat a bug quickly consume the first ones above ground.

The weather in late April and early May was a seesaw, often unfriendly and even cold in the evenings when cicadas prefer to emerge from their 17-year underground lairs. The first full weekend of May saw thunderstorms and heavy rain, while the initial 12 days of the month saw daytime temperatures in the 60s, nighttime in the 40s. That’s hardly cicada friendly.

The only reason the cicadas climb above ground is for males and females to find each other and reproduce before they die. It’s a Romeo and Juliet kind of scenario, but I am not sure if the Bard’s famous couple ever got to consummate their union. Despite the inclement weather, the cicada reproduction urge is strong. The future generations depend on it. I saw my first true handful of adult cicadas at a friend’s house, local artist Vickie Henderson, on May 10.

But finally the weather changed and the last half of the month became cicada hot. Temperatures stretched into the high 80s and 90s and Cicada-palooza swung into high gear. And what is high gear? After the larval cicadas crawl from the ground, molt and let their wings dry, the males fly to the ridge tops to drone, making an eerie sci-fi sound by vibrating their abdomens. With numbers in the millions at some locations the mournful drone can be heard from a great distance; that is what attracts the females to the males’ brouhaha.

On May 16, I found oodles at Seven Islands State Birding Park thanks to a tip from park naturalist and ranger Clare Dattilo. It was that way for the next two weeks in almost every public park I visited, with perhaps the loudest male droning heard on May 24 at Haw Ridge Park on Edgemoor Road in Oak Ridge. I was there with UT Arboretum education director Michelle Campanis on a tip from Ruth Anne Hanahan, who had hiked the park a few days before. Brood X was also exquisitely loud on the south side of the river at Charter Doyle and I.C. King County Parks on May 31 during a visit with Rachael Barker.

But the very next day, June 1, I knew the peak had passed with hundreds of dead cicadas on the greenway at Holston River Park. The males droned on loudly for a few more days but the party was winding down. Once mated, the females lay their 200-plus eggs and then die. It had been a wonderful natural phenomenon that, with cool days and rainy days, lasted roughly seven weeks.

There were still pockets of late arriving males around the valley into June. But their droning became softer and softer until it flickered out.

Studies conducted in part by Bard College professor Felicia Keesing in 2004 determined that the sudden appearance of thousands of dead cicadas on the forest floor caused a dramatic spike in nitrogen in the soil. A later look at tree rings found a bump in growth every 17 years. Keesing compared it to someone pouring a pound of fertilizer per square yard throughout the forest where the cicadas were found, underscoring yet again that nature has profound cycles, although some are easier to observe than others.

What’s next? Brood X will be back in 17 years when this year’s larvae climb from the ground in 2038. If you can't wait, there is always Brood XIII, centered in Illinois, in 2024.

After 17 years underground and near the end of their lives, the cicadas climb from the ground where the males and females find each other and mate, dying shortly thereafter. Photo courtesy of Stephen Lyn Bales