I know you’ve probably satiated your appetite for knowledge about our seventeen-year cicada by now. But, you’ve got to admit, they are amazingly unique.
You don’t have to go any further than the zoological name to begin to understand the uniqueness of this species. Carolus Linnaeus, himself, bowed to its’ special nature, by giving it the generic (or genus) name Magicicada. Linnaeus had a practical side, as well. The specific epithet (or species) name he chose was septendecim; Latin for seventeen.
While some articles suggest the seventeen-year cicada is the world’s longest living insect, my contacts say otherwise. While it may be true that this cicada may be the longest living as a species, the longest living insect was thought to be either the queen bee or queen termite, who has been documented to live as long as 30 years! And then, someone documented an individual wood-boring beetle larva that emerged after 51 years!
Many articles suggest it may be the loudest insect in the world. At 120 decibels, these insects are louder than lawnmowers (90-100 db) or car horns, (100 db), and just as loud as chain saws. Sounds reaching 90 db are known to damage hearing. I have read of no insects that make louder noise, er, music; at least, so believes the female.
Speaking of music, you would think the vocal males would have no problem attracting females. Yet, they still compete for their attention. The males routinely produce four different ‘songs’ in their effort to win the affection of the females. The first calling song, the sing-fly, is used to lure the female to his whereabouts. When he detects the hormones of several females, he lands on a twig and begins the first of three courting songs (known as CI), in which the female joins in song with him by ‘flicking’ her wings. Getting a little excited, he will walk along the twigs in her direction, and begin the next song (CII). As he finally makes contact with the female, he begins a final triumphant song (CIII), which he continues until the final climatic moments of his 17-year life.
Did you know you can tell the very night the cicadas will emerge? Take the temperature of the soil. The cicadas, like all creatures, need a certain amount of energy to conduct their activities. When the soil temperature reaches 64°F, they have the necessary energy to turn the systems on. In fact, the weather can cause a majority of the insects to emerge on a single night.
So, how many can emerge? Records have documented population densities as high as 1.5 million per acre, although densities of tens to hundreds of thousands per acre are more common. Why so many? It’s called ‘predator satiation’. So many cicadas are produced, it simply overwhelms the gluttony of any and all predators. This is similar to the infrequent ‘mast years’ of oaks and other woody plants and not too dissimilar to the massive broods of mayflies in the spring.
Let’s face it. Cicadas are great fast food. Easy to find, easy to catch, and easy to consume. Good for you, too. So popular are cicadas, they must do more than just emerge in massive quantities to survive. They also emerge unexpectedly. As you probably know, not only are there seventeen-year cicadas, but there are thirteen-year cicadas, as well. And what makes that unexpected? Realize that 17 and 13 are prime numbers, divisible by only itself and one. This means predators with a shorter life cycle (read that, all predators) cannot synchronize their life cycles with those of these cicadas.
So, let’s talk a bit about cicadas, in general. There are over 100 species known in North America. Apparently all species emerge only after spending several years underground. Even our ‘dog-day’ annual cicada spends two to four years sucking on roots before emerging. They just aren’t synchronized for emergence, like the seventeen and thirteen year cicadas, so some emerge every year. Only three species emerge on a seventeen-year cycle and four species emerge on a thirteen-year cycle. Interestingly, each 17-year species has a 13-year counterpart species, from which it can be distinguished only by life cycle and geographic distribution. For the time being, taxonomists prefer to keep them as separate species.
Speaking of geographic distribution, the seventeen-year cicada emerges somewhere in eastern US almost every year. Each yearly population is called a brood. There are 12 broods of 17-year cicadas (with the remaining five year classes apparently containing no cicadas), and 3 broods of 13-year cicadas (with ten empty year classes). Each brood of 17-year cicadas consists of all three species, with the exception of brood VII, which is found on the northern edge of the cicada’s range. The 13-year cicadas are less inclusive.
This year’s population (brood X) is the largest of the
17-year broods, with cicada emergences expected in parts of fifteen states,
from New York to Georgia to Illinois. Adults will start appearing in Virginia in early May
with numbers peaking in early June. Numbers decline by late June and most
cicadas are gone by July. Note that most of Virginia will not be affected this
This year’s population (brood X) is the largest of the 17-year broods, with cicada emergences expected in parts of fifteen states, from New York to Georgia to Illinois.
Adults will start appearing in Virginia in early May with numbers peaking in early June. Numbers decline by late June and most cicadas are gone by July.
Note that most of Virginia will not be affected this year.
We don’t have any 13-year cicadas in our region. These more southerly species get only asclose as extreme SE Virginia, with the next emergence expected in 2011.
These amazingly unique creatures will only be around forabout four weeks. After six to tenweeks, the eggs hatch and the new first-instar nymphs drop from the tree twigsand burrow underground to start the next seventeen-year cycle. I wonder what our world will be like whenthey emerge in 2021?