Last week I answered lots of questions and did a few interviews bringing the sad news that periodical cicadas will not appear in the Baltimore–Washington metro area this year. Twelve years ago states bordering the Mississippi and those eastward from the Carolinas to New England were treated to trillions of red-eyed insects known as Brood X periodical cicadas. Like some strange biological equivalent of Haley’s comet, these boisterous bugs were touted as a phenomenon that occurred only once every seventeen years. This was a source of despair for those that loved them and a source of relief for those that didn’t.
Part of the story not known to all was that in other parts of the country other broods of cicadas are found in intervening years. In fact, there are 12 broods of 17 year cicadas and three broods of 13 year cicadas. So it was with delight and fear that many recently heard the news that cicadas were coming in 2016, and they are - just not around DC and B’more. Brood V cicadas are about to make their debut in extreme western Maryland in Garrett County, a tiny southwestern portion of Pennsylvania, Virginia primarily west of I-81, much of West Virginia, and much of eastern Ohio. To see a map of their distribution, click on this link:
However, those lucky enough to live in the infested area are in for a real treat. Yes, infestations of some bugs can be delightful. The life of a periodical cicada is mysterious and precarious. After consuming xylem fluid from the roots of plants underground and completing their juvenile life there as nymphs, each cicada constructs an escape tunnel to the surface of the earth. Soil temperatures in the middle sixties are the cue that the world above ground is warm enough to support flight and reproduction. Many nymphs emerge at night and make a mad dash for vertical structures such as trees and shrubs, however, lampposts, street signs, and slowly moving people seem to work just as well. After climbing up and away from the soil, they attach to a firm object to begin the process of molting.
Amidst the chorusing of broodmates, a nymph struggles to escape from its subterranean crypt.
Their outer skin, or exoskeleton, splits along a predetermined line on their back and the beautiful adult cicada wiggles free from the shell. The freshly molted adult is almost pure white except for bright red eyes and patches of black behind the head. Before its skin hardens, the cicada must expand its wings or it will be unable to fly and seek a mate. After wings and legs have hardened, cicadas scurry or fly to the treetops. Emergence from the earth and the final molt are perilous times for cicadas. Many cicadas survive interment underground for seventeen years only to perish attempting to molt and reach the safety of the trees.
If they can survive the perils of shedding their exoskeleton, cicadas make a mad dash for the treetops.
The big noise in the treetops, the hallmark of periodical cicadas, is all about love baby, yeah. Male cicadas have evolved a unique structure called a tymbal. These paired organs are located on the sides of their bodies just beneath the wings. Through muscular contractions, males vibrate the tymbal much like a drumhead to produce sound. Males produce a variety of calls for different purposes. If threatened by a predator such as a bird or a bug geek, a loud squawking noise is made in attempt to startle the predator and make an escape. The principal function of the tymbal is to produce calls that assist in finding a mate and winning her affection. One type of call attracts both males and females to a common assembly place such as a large tree. When guys and gals get eye to eye, the male will use three distinct and different courtship songs to try and convince the gal that he should be the father of her nymphs. If the lady likes his advances, she will signal her approval by flicking her wings with an audible click.
Vibrations of the tymbal are used to frighten giant fingers and predators and also to attract mates in the treetops.
After mating, the female cicada moves to tender young branches to lay eggs. Using a saber-like structure on her abdomen called an ovipositor, the female gouges groves into the woody tissue and lays 20 to 30 eggs in an egg nest. This process is repeated on one or more plants. Females lay as many as 600 eggs. After incubating for more than a month, eggs hatch and tiny nymphs a few millimeters long dive to the earth beneath the tree. In a matter of minutes, they burrow into the soil, find roots, and insert a small straw-like proboscis into the roots. Cicada nymphs hunker down underground sipping sap and slowly growing larger. Despite what you might have heard, cicadas are not blind. Their red eyes see fine. They do not bite, although, if very thirsty, one may probe you a bit with its tiny beak in search of moisture.
Periodical cicadas are not one species. Broods of 17 year cicadas are comprised of three distinct species and 13 year broods often contain four. Many mysteries remain concerning their evolution, distribution, and synchronous appearance. Without a doubt, they are a true marvel of nature and one that should be enjoyed whenever possible.
DC and Baltimore: I fibbed a bit when I said that cicadas are not here this year. They really are – a foot or so beneath the surface of the earth – billions of them, maybe trillions of them. And five years from now in the spring of 2021 we will again be treated to the big boy band up in the tree tops as one of Mother Nature’s most curious events unfolds. Get ready!
To have a sneak preview of what Brood V will look like, watch my visit to Brood XIII in Chicago in 2007. Please click on the following link: