On a warm summer’s evening in May, 2004, I had the remarkable good fortune to witness one of Mother Nature’s most spectacular events, the emergence of hundreds of Brood X periodical cicadas at my home in Columbia, MD. While anxiously counting down the years to 2021, the next appearance of Brood X, I’ve had my eyes open and downward cast searching for evidence of cicadas in the form of exit holes and mud turrets in the soil. Last week my vigil was rewarded with the sighting of several galleries occupied by fully developed cicadas almost ready to make a jailbreak into the world above ground.
In previous episodes we visited boisterous periodical cicadas from Brood II in Northern Virginia, Brood XIII in Chicago, and Brood XIX in St. Mary’s County Maryland. Last year spectacular Brood V were featured as they emerged in Morgantown West Virginia. We also noted the appearance of some cicada “stragglers” in locations in central Maryland far removed from the main event further west. Stragglers are periodical cicadas that emerge “off cycle” in years prior to or after their major brood appears. Often, 17 year cicada stragglers appear four years prior to their expected emergence date; however it is possible for periodical cicadas to emerge between 8 years earlier and 4 years later than expected.
This week we get a sneak preview of the far flung Brood VI periodical cicadas. While the bulk of Brood VI will be found in parts of South Carolina, North Carolina, and Georgia, other parts of this brood are expected in Ohio and Wisconsin. Now here is where the story gets interesting. According to Cicada Mania, the reliable source for all things cicada, historical records indicate that in years past Brood VI cicadas were observed in Delaware, D.C., Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, New York, Oklahoma, Pennsylvania, Tennessee, Virginia, and West Virginia. Several hypothesis have been advanced to explain these observations. One has it that periodical cicadas observed in some locations are stragglers from last year’s Brood V that just took one year longer to develop and are now arriving along with Brood VI in 2017. A second hypothesis, one I am quite fond of, posits that some of the cicadas found in locations in Maryland are part of the Big Brood, Brood X cicadas, courtesy of a curious developmental phenomenon of periodical cicadas known as acceleration. Accelerations occur when a portion of a cicada brood emerges years in advance of billions of cicadas comprising the bulk of their ginormous synchronous brood. Four year accelerations including some associated with Brood X have been observed in Washington DC, Chicago, Cincinnati, and other parts of the Midwest.
While the mystery of exactly which cicadas are on the move in my yard and our region remains unresolved, it is clear these teenagers are about ready to roll. After a bit of patient observation of one hole, I was greeted by an inquisitive periodical cicada nymph that ventured to the top of its gallery to have a peek at a bug geek. After administering the cicada equivalent of an RAF salute, the smallish nymph retreated to the depths of its subterranean chamber to await the precise moment to make an escape into the wonderful and treacherous world above ground. When will this moment take place? For seventeen or thirteen years Brood VI and Brood X nymphs, respectively, have been marking time underground since hatching from eggs by counting annual fluxes of hormones or amino acids in xylem sap or by some yet unknown internal clock. Regardless, if this is indeed an acceleration of Brood X cicadas or a regular emergence of Brood VI, the nymphs are waiting for soil temperatures to reach the middle 60’s. This marks the time that the world above ground is warm enough to support activities of feeding, besting predators, finding mates, and laying eggs in the treetops. In addition to cicada galleries in Columbia Maryland, periodical cicadas have been observed in Bowie, Annapolis, and College Park.
After popping up for a quick look at a human with a camera, a periodical cicada nymph descends deep into its subterranean gallery to wait for the world above ground to warm just a bit more.
If you are lucky enough to live in parts of South Carolina, North Carolina, Georgia, Wisconsin, and Ohio you may witness the spectacular emergence of Brood VI cicadas that will soon be underway. Here in the DMV and throughout the ranges of Broods VI and X, let’s wish the best for these bold teenage adventurers and hope their numbers are large enough to give us a thrill while they escape enemies and find mates.
To learn more about all things cicada, please visit the following website:
CALL TO CITIZEN SCIENTISTS: we need your help! If you see periodical cicada nymphs, shed skins, adults on vegetation or in trees, please report your sightings to magicicada.org. Cicada experts are attempting to map the distribution of these magnificent and magical insects. Thank you for your help.
We thank entomophile Gaye Williams for providing the inspiration for this episode. Two wonderful articles, “Evolution of 13- and 17-year periodical cicadas (Homoptera: Cicadidae: Magicicada)” by C. Simon, and “The ecology, behavior, and evolution of periodical cicadas” by K. S. Williams and C. Simon, were used to prepare this episode.