Cicadas are confusing little buggers. Or bugs, if you like. “Large insects” if you want to be technical. When I was a kid, my understanding was that there were two kinds of cicada: annual and “seven-year.” False! I also thought the annuals lived their whole life cycle in a single year, whereas the seven-year variety hibernated underground for the years between emergences. False! I probably also thought a lot of other false things about cicadas, but those are the things I remember.
Fortunately, biologists have this cicada thing on lock. Magicicada.org has a wealth of information on periodic cicadas (those of the genus Magicicada). There are seven known species of Magicicada, three of which have a seventeen-year life cycle and four of which have a thirteen-year life cycle. Most of a periodic cicada’s life is spent in its nymph stage, tunneling below the ground in search of food. The entire generation (locally) emerges at once to metamophose into its adult stage. The adults explode into several months of noisy mating then die as their progeny hatch and head back underground.
Scientists have grouped the emergences into “Broods,” each of which is designated with a Roman numeral and has a predictable 17 or 13 year cycle. Broods may comprise one or multiple species. Occasionally a brood of 17-year cicadas overlaps with a brood of 13-year cicadas for a completely bonkers display of insectery. There are also often “stragglers” appearing in the off years – the term is used to refer to both early and late individuals.
Why am I talking about this now? The Washington, DC area is next due for a brood (Brood X) of Magicicadas (the 17-year kind) in 2021. Yet people in the area have been reporting sighting of Magicicada for the past few weeks. I photograpphed one on 5/6 but assumed it was an annual cicada. Laurel asked me a few days later why we were seeing so many, and I assumed it was just a good year for the various annual species. Then I saw a couple of articles about it, and on 5/18 I counted over a hundred individuals in my backyard over about fifteen minutes. It seems there are quite a lot of stragglers, and a full four years early.
A brief aside about those annual cicadas: First, these aren’t a single species either but many species distributed among several genera. I think the most common, or at least the most reliably identified, is sometimes called the “dog day” cicada, Neotibicen tibicen. Anyway, it is not a one-year lifespan that makes these species “annual.” These cicadas also live several years, mostly as nymphs. The difference is that the ages of individuals are staggered – they do not all reach adulthood in the same year and therefore are not all on the same breeding clock. This is an enormous distinction and serves to illustrate just how odd the breeding of periodic cicadas is. Can you imagine if every adult human produced offsprinng once every seventeen years and never in between? Picture the media frenzy each cycle in the months leading up to “sex year.”
Back to the periodics. What is going on here? Is the whole brood going to emerge this year, or just an unusually high and concentrated group of stragglers? Are all three species part of this phenomenon? If it is the whole brood, is the cycle just going to advance for four years in perpetuity? Will the next one overcompensate and last 21 years? Is Brood X about to switch from a 17 to a 13 year cycle? For all of these questions, add: why?
Is it Climate Change? I have seen this assertion many times already, and I’m not sure how well it stacks up. I can’t imagine the trigger to emerge after 17 years is temperature, but Climate Change is must more complex than just rising temperatures. It would be emotionally satisfying to have one more example of the chaos wrought by Climate Change, but for this very reason I am unwilling to assume it is the case and accept the easy answer.I’ll be fascinated to see what cause entomologists do attribute this too (I bet it’s not chemtrails or GMOs, WINK) and how they go about figuring it out.
YOU can help the entomologists get there by reporting sightings here. It’s a remarkably easy online mechanism that only takes a few minutes, and every data point is helpful. So if you see cicadas with big red eyes consider doing your part.