Temperatures were in the upper 80s two weeks ago as I trudged across campus for a review session with nervous students prepping for a final in biology. The sweltering, clammy calm of the afternoon was interrupted by a lonesome call of a male periodical cicada high in the top of a willow oak tree. With this announcement, the 2018 periodical cicada season was officially underway.
Holes in the ground, shed skins on leaves, and adults ready to ascend to the treetop… yep, cicada season is underway.
In the intervening week, I received two reports confirming the arrival of adult cicadas in Bowie and Columbia, MD. A recent afternoon jog around the neighborhood in Columbia revealed shed skins on several majestic elms, oaks, and lindens, where hundreds of cicadas were spotted last year. Entomophiles are already awaiting the return of Brood X cicadas scheduled for 2021. Last year we had a sneak preview of this event in many neighborhoods in the DMV with the appearance of thousands of cicada “stragglers”. 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 several years earlier or later than expected. According to Cicada Mania, the most reliable source for all things cicada, historical records indicate that part of “the Big Brood”, Brood X cicadas, undergo a curious developmental phenomenon known as acceleration. Accelerations occur when a portion of a cicada brood emerges years in advance of the 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, and in Chicago, Cincinnati, and other parts of the Midwest. In several areas, last year’s stragglers emerged in numbers sufficient to best hungry predators and survived long enough to reproduce and lay eggs. With any luck their progeny will emerge in spring some 17 years in the future.
Brood X stragglers have already been reported this year in Cincinnati, Ohio and Bloomington, Indiana. I think we can add Bowie and Columbia, Maryland to this growing list. However, after discovering a local Columbian cicada patch, I returned early one morning to find it had turned into a cicada killing field as mixed swarms of several bird species picked off scattered cicadas that had emerged overnight. You see, without millions of their broodmates to fill the tummies of hungry predators, these stragglers were likely doomed to perform the Darwin experiment: emerge prematurely and remove your genes from the population. Cicadas pay a heavy price by not following the rules of their ancient strategy of predator satiation, a plan that depends on an enormous synchronous emergence that simply overwhelms the capacity of predators to consume a tsunami of cicada prey. While I always root for the cicada, I fear numbers are too slim for cicada success this year.
In the cicada killing fields, pileated woodpeckers seem to search a tree while a tufted titmouse enjoys a tasty cicada for breakfast in branches above.
The real deal brood of cicadas emerging in 2018 are those of Brood VII, the ill-fated Onondaga Brood. The range of this brood, which once occupied at least nine counties in the Finger Lakes region of New York State, has declined dramatically in recent decades. Experts fear it may be the next brood to go extinct, joining Brood XI that disappeared in Connecticut. Cicada Mania points to the usual suspects of habitat destruction due to agriculture and urbanization, habitat degradation due to several factors including pesticides, and natural events such as persistent floods that smother cicada nymphs in their subterranean lairs, as the underlying causes of these declines. Magicicada cassini, one of the major participants in Brood X, utilizes ash trees as a favored host for egg laying. Emerald Ash Borer, dastardly destroyer of more than 100 million ash trees in 20 states where cicadas are found, certainly hasn’t helped the plight of our periodical cicadas.
If you want to see periodical cicadas in all their glory, your best bet would be to head for the Finger Lakes region of New York near Rochester to have a look, maybe the last look, of these strange and magnificent creatures of Brood VII. Here in the DMV, keep your eyes and ears open for the next several weeks, and please participate in the citizen science project listed below to track these magical creatures. Happy cicada hunting!
CALL TO CITIZEN SCIENTISTS: we need your help! Cicada experts are attempting to map the distribution of these magnificent and magical insects. If you see periodical cicada nymphs, shed skins, adults on vegetation or on trees, please report your sightings to: http://magicicada.org/magicicada/mapping-updates/
Thank you for your help.
To learn more about all things cicada, please visit the following website: http://www.cicadamania.com
We thank entomophile Gaye Williams and picture taker Nancy Perkins 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, and information at Cicada Mania were used to prepare this episode.