By Dr. Robert Thorson
I have insect envy. Cicada envy. Right now, I wish I could be watching and hearing these noisy, redeyed, prune-sized, flying bumper-car bugs in the woods behind my Connecticut backyard. But I can’t because the habitat range of this year’s crop of these extraordinary insects reaches only as far north as Long Island.
Every day this spring I have lived with the knowledge that I am missing a rare spectacle of nature, one that does no harm, yet reminds us how overwhelming the power of life can be. This year’s spectacle — unique to the United States — is the coming-out party for Brood X of the genus Magicicada, which happens only once every 17 years, something like a plague of locusts without the locusts.
Being an optimist, I look for a silver lining in every cloud of cicadas. I think it’s great that most people don’t share my cicada envy. Apparently, they don’t want their wedding or graduation parties ruined by an alien invasion that seems to come out of nowhere. They don’t want to hear the deafening noise that sounds like a fleet of high-pitched helicopters. They don’t want to rake bugs from their driveways and yards in the spring, having already done so with leaves in the fall. They don’t want to smell the aroma of the decomposing bodies of sap-bloated insects wafting on spring breezes. For those of you who are insect-avoidant, insect-apathetic or insect-squeamish, please understand that massive cicada invasions — with up to 1.5 million individuals per acre — could become a consequence of global warming.
Many people have arachnophobia, an unusual fear of spiders. Perhaps cicada-phobia will prompt at least a few additional residents of the New England states into personal and political action on climate change. A northward shift in the range of Magicicada is one of thousands of ecological adjustments that will likely take place as the climate continues to warm rapidly. Perhaps you don’t care if the sugar maples migrate into Canada, or if trout can no longer survive in freshwater streams. Perhaps the spread of West Nile virus doesn’t concern you. But if cicada-phobia is your thing, if you are alarmed by a potential invasion of the body droppers, if this is the ecological adjustment that touches your panic button, then that’s great news for the environment. Why? Perhaps it will motivate you to reduce your own consumption of gasoline and heating oil. Maybe it will bring you to vote for political candidates who support either a national commitment to a sane energy policy or a local commitment to stop suburban sprawl, which forces longer drives and pre-empts trees from soaking up extra carbon.
When the cicadas do come, they will bring with them two valuable lessons for the next generation of New England schoolchildren. The science lesson concerns the “feast or famine” evolutionary strategy used by creatures the world over. By coming out all at once, predators become overstuffed, unable to take even one more bite of cicada, leaving plenty left to perpetuate the species. The math lesson concerns prime numbers. Using an internal clock not yet well understood, natural selection has timed cicada outbreaks to be either 13 years or 17 years, but nothing in between. By having such lengthy and prime-numbered underground stages, the aboveground predators haven’t been able to evolve mechanisms to keep track of, and therefore exploit, the brief oversupply of food. As a group, cicadas have learned the significance of prime numbers, which is a pretty neat mathematical idea.
There are other cicada broods that do reach southern Connecticut, but they are smaller, happen in other years and are far less compelling. For northern Connecticut, and for the whole state this year, the closest thing we have to the cicada symphony is the chorus of spring peepers, small frogs that also use a burst of noise in their mating rituals before becoming quiet for the rest of their lives. I wouldn’t trade the tumult of peeps from our vernal pools for the high-pitched drone of cicadas in the deciduous forest because I don’t want the climate warming that would come with it. It’s hot enough already.