Category Archives: Cicadas

17 year cicadas

The seventeen year cicadas are emerging in the Northeast, so they’ve been in the news quite a bit of late. One video in particular is worth watching: Sam Orr’s mix of time-lapse and real time video of the complete life cycle. He has been working on this project for several years and has filmed parts of the life cycle that are seldom seen. You can read more about his work here.

To learn more about where (and in what year) these creatures emerge, visit this page or this one.

For those lucky enough to live where the action is, remember what you’re hearing: seventeen years of stored sunlight being released all at once as acoustic energy. The terrestrial end product of nuclear fusion exploding into your consciousness.

Sewanee cicada: ours are on the thirteen year plan.

Sewanee cicada from back in 2011: ours are on the thirteen year plan.

For literary/musical engagement with these insects, I recommend David Rothenberg’s Bug Music, which has just recently been published. I was honored to “blurb” the book and here is what I had to say:

“Fabulous entomological jazz: David Rothenberg draws together disparate strands of inspiration and writes a new song, full of unexpected riffs and harmonies. Bug Music is a thought-provoking celebration of the acoustic bonds between humans and our insect cousins.”

In other words: a treat and an education for the mind and the ears.

Emerging from the underworld

They’re back. Cicadas are crawling out of the hypogeal darkness. Summer must be coming, hidden somewhere behind the cold, rainy clouds.

Cicada emerging 009 This pallid nymph was hauling itself out of a hole in the trail. The front legs are mole-like: sharp-edged shovels. After the insect’s molt, which usually happens shortly after emergence, the shovels will turn to grappling hooks, a more elongate form suited to clambering in trees. The molt will also equip the adult cicada with wings (wing buds are visible on the nymph’s back in the photo above).

Cicada emerging 013This is a so-called “annual” cicada, a name that belies the two or more years that the nymph has spent below ground. Although individual cicadas take more than one year to develop, there are multiple cohorts present in every location, so at least some of them emerge every year. This contrasts with the “peridocial” cicada species whose cohorts are synchronized, emerging every thirteen or seventeen years. Sewanee had one such emergence back in 2011. The New York region is due for an emergence this year, so we can expect some cicada media coverage in the coming weeks. (To find out whether or not you’re in the emergence area, see here for maps of the various “broods” of periodical cicada — the NY brood for 2013 is Brood II.)

Cicada killer

Stop and listen. Every tree is occupied by buzzing cicadas. Their vigor of their acoustic attack builds through the day, then dies away after dark, giving way to katydids.

We’re not the only species to tune into this sound. Cuckoos, blue jays, and other large-billed birds will grab cicadas when they can. But the champion hunter is the cicada killer, Sphecius speciosus, a large wasp that flies up into the trees in search of its prey.
The wasp grasps a cicada then tries to jab its stinger into the weak spots on the cicada’s exoskeleton. The cicada reacts violently — fighting for its life — buzzing its wings, writhing, and rolling. Often the tussling pair fall to the ground as they struggle. The cicada tries to break free while the wasp lances with the sharp stinger on the end of the abdomen. Spear and armor clash, then resolution comes. If the cicada can free itself, it takes wing and zooms away. The wasp does not follow, having no hope of recapture. But if the wasp’s poison finds its mark, the cicada falls into a deep sleep. This is no fairytale, no prince comes to waken the sleeper; instead, the mother wasp carries her prey to an underground tunnel where she buries it, alive but paralyzed, with a wasp egg. The larval wasp will fuel its growth by consuming the cicada.

Cicada killers have been active these last several weeks. They prefer to build their tunnels in well-drained sand, so the upper portion of the Lake Cheston “beach” has numerous holes, as do other sandy areas in town.

Cicada killer with paralyzed cicada. The wasp was dragging her prey across the sand toward a burrow.

The wasp is almost as long as my thumb. They look fearsome, but don’t attack humans unless molested. Unlike yellowjackets and bees, cicada killers don’t defend their nests from intruders and can be observed at close range.

Entrance to nest burrow. The cicada pictured above was laid to “rest” here.

Cicadas are big insects and the wasps often struggle to carry them. I was swimming in Lake Cheston a few days ago when a low-flying creature — I thought at first a hummingbird — flew across the water, losing altitude as it went. When it reached the lake’s center, the flier hit the water’s surface, dropped its excess baggage and shot away. I swam out to retrieve the cargo: a cicada bobbing on the water. Back on shore, Junebug (the dog, not the insect), wanted a look. Lacking a burrow and an egg, we left the cicada to its unfortunate fate.

Visual confirmation of the waaa-oo cicada

…also known as Magicicada tredecim. I’ve been hearing them for weeks, but this is the first one I have managed to catch and examine closely. Regrettably, all the thirteen year cicadas seem to be fading away now. So long, until 2024…

Magicicada tredecim. Underside of abdomen is mostly orange. Compared to Magicicada tredecassini, which is often found at ground level, this species seems to prefer the treetops.

Getting ready for the year 2024

This female cicada was laying eggs today on the spicebush outside our house. She makes a small slit in the stem, then deposits eggs in the opening. The eggs remain on the twig for a few weeks, then the nymphs hatch out and fall to the ground. Here, they burrow down into the soil and live for thirteen years, feeding on tree roots. The Class of ’24 is underway.

Magicicada tredecassini depositing eggs from the tip of her abdomen

And, for some remarkable timelapse photography of an emerging cicada, see Mark Dolejs’ Vimeo post.

Which species of periodical cicada do we have here?

According to the website, three species are possible in Sewanee:

Magicicada tredecim — Underside of abdomen is mostly light orange/caramel. These are the ones that call waaa-oo from the treetops.

Magicicada tredecassini — Underside of abdomen usually all black, or with faint orange lines.

Magicicada tredecula — Well-defined orange stripes across underside of abdomen.

This individual crashed into my head while I was watering the garden, so I brought him down with the water jet and did some catch-and-release identification: Magicicada tredecassini. The sound he was making seems to match that on the magicicada pages also.

Cicadaroo comes to Sewanee

Here they are! It is finally hot enough for the cicada choir to crawl out of the soil and shake our senses with their sunlight-made-into-sound, a concentrated celebration of a dozen years of Tennessee’s lush photosynthesis.

Early in the morning, they start with the waaaa-oo waaaa-oo chorus call from the treetops. As the day heats up, their raspy courtship calls dominate, interspersed with the wing-clicking of females.

You can hear both the ghostly waaa-oos and the louder rasps in this recording that I made with a Zoom H4:

Cicadas in Sewanee, update

So far, the thirteen-year cicadas have been much more active in the valley than on the mountain. There are a few buzzing around Hat Rock Rd and Willie Six Rd, but most places in Sewanee have no cicadas. They may still be on their way, the soil here being cooler than in the valley. However, thirteen years ago the cicadas were also much less common in Sewanee/Monteagle than in the lower surrounding areas.

90 decibels…

…is how loud the 13-year cicadas were when I made a pilgrimage to Sweeten Cove to listen to them this afternoon. The CDC recommends that humans limit their exposure to any sound louder than 85 dB. I can see why — my ears were ringing after spending half an hour in the midst of a cluster of cicadas.

Thirteen-year cicadas pulse the loudness of their sounds every four or five seconds (top graph). Their hissing, buzzy sound is concentrated in the middle and high ranges (bottom graph; for comparison, humans talk below 1 kHz). I made these recordings standing under a hackberry tree that was swarming with cicadas, then used Raven to draw the graphs.