The arrival of Brood X periodical cicadas—while patchy in Central Indiana—has given us all something to talk about. Love them or leave them, hate them or taste them, their 17-year emergence is a memorable one.
Dr. Elizabeth Barnes, entomologist from Purdue University, shared her expertise during our “cicada happy hour” recently. Bug-lovers young and old gathered at Oliver’s Woods to learn more about these fascinating insects.
With a 17-year cycle, data on these funny-freaky bugs can be a bit spotty. Their range used to be tracked in a fairly low-tech way: Researchers would drive around with their windows open and listen. If they heard the cicadas’ voices, they’d note their presence.
As Dr. Barnes pointed out, we see cicadas for a mere fraction of their lives. And what we think of as a cicada is just the form they take during this one short phase of their entire lifespan. For about six weeks, these adults amass in large (and loud) numbers to mate. The females lay eggs on young trees, and then the bugs die.
But their young (nymphs) will burrow into the ground under the trees and start feeding and molting over the next 17 years, till their next emergence.
After her overview, questions came fast and thick as the cicadas that have emerged at places like Blossom Hollow in Johnson County.
Is it true they don’t have mouth parts?
Not true, adult cicadas can ingest small amounts of sap from trees.
How do they make that buzzing noise?
The males have a special organ called a tymbal that they can vibrate like a bendy straw. (Females make a sound like a finger snap with their wings.)
Why do they “sing” only during the day?
As insects, they have no internal heat source and must wait for the day to warm up before they can be active. They sing between 10am and 5pm because that’s when the day is warmest.
Is it true you can attract a male by snapping your fingers?
If a male is flying low enough, you can snap your fingers to imitate the female’s sound, and the male will come near. (Watch David Attenborough do just that.)
These little guys are good at math! How, why?
One outdated idea was that the nymphs molt 17 times and then come out, but that’s been debunked. The current theory is that their emergence is based on cycles of trees, as the nymphs are under the ground sipping from tree roots.
Do they harm the trees?
They evolved alongside our native trees, so they are unlikely to harm them through feeding on their sap underground. Very young trees sometimes struggle to recover when the female adults lay eggs on them.
I read that the DNR gives away $100 if you bring them a blue-eyed cicada, is that true?
There is a persistent story about this mythical blue-eyed cicada—a supposedly rare phenomenon that, sources often say, Indiana DNR will pay you $100 to collect. In truth, the cicadas have red eyes, but when they first emerge, their eyes look milky. This might pass for blue… but there is no $100 payment for collecting them. Sorry!
Will there be a bird boom next year because of Brood X?
Bird populations are expected to increase next year where Brood X has emerged. Cicadas’ emergence means that a large amount of biomass that had been underground for 17 years…is now above ground and available. This benefits birds in two ways. It gives them a plentiful food source, which helps the survival of their chicks. It also gives their predators, such as raccoons, an alternate food source, so more baby birds escape being eaten.
What can you tell us about the pathogen that specializes in cicadas?
There is just one: a fungus, and it is simultaneously gruesome and fascinating. It infects the cicadas and replaces the entire abdomen with the fungus. On the males, it affects their brain function, making them stay active though they’ve lost half their body. Infected males click their wings like a female to attract other males. This rapidly spreads the fungus.
On that tasty note, everyone gathered for refreshments, including a “cicada tasting” (optional) (a surprise to the CILTI staff). In case you are curious: baked cicadas taste a bit like charred chicken skin, without being greasy. Safety note: Only try them if you have no allergy to shellfish.
Here’s to the wonders of nature!