In my town, the distinct sound of cicadas humming marks the arrival of the summer heat. It is a comforting sound, that reminds me of summers gone by and the carefree life of childhood. However, if you see these unsightly little fellows up close, you might not be so fond of them. Most people would find them pretty scary with their strange clear wings, bulging eyes, and large size. According to entomologists, these critters will be making an appearance this summer throughout parts of Virginia, West Virginia and North Carolina and the numbers could be startling. We’re talking as many as 1.5 million insects per acre. I would imagine that hum will reach deafening decibels with those numbers! (1)
17 Year Cicada Cycle
Some species of cicadas emerge every 13 to 17-years after living underground as nymphs. Populations of cicadas are called broods. This brood made their last appearance in these parts in 2003. There are different species of cicadas which determines when they will emerge. The ones in my neck of the woods for example come out every year. The species in and around Virginia, West Virginia and North Carolina however, are considered “periodical” because they only emerge every 17-years. It is unclear why their appearance is so specifically timed. (1)
Cicada Choir
“Communities and farms with large numbers of cicadas emerging at once may have a substantial noise issue,” says Eric Day, Virginia Cooperative Extension entomologist at Virginia Tech’s Department of Entomology in the College of Agriculture and Life Sciences. “Hopefully, any annoyance at the disturbance is tempered by just how infrequent—and amazing—this event is.” (1)
Males make their distinct sound by flexing a drum-like organ called tymbals. The flexing causes the sound in their rather hollow abdomen. The females are the quiet ones of the species. (2)
From Nymphs To Cicadas
During their time underground, the immature nymphs live in the soil before shedding their skin and becoming adults. Soil temperature and the time of year trigger the cicada’s emergence. The insects use the cycle as it naturally allows them to improve their chance of survival and reproduction. The cycle is considered one of the greatest mysteries in the insect world. (1)
Cicadas Avoiding Predators
Despite the mystery there is much speculation about why the cycle exists. One suggestion is that the insects might be trying to avoid predators. Birds that feed on the cicadas can very aggressively and quickly eat entire populations of cicadas if the insects emerge too soon. In fact, one older study reported in The American Naturalist drew a connection between declines of predatory bird populations and the cicadas’ 13- and 17-year cycles. (1, 3, 4)
Cicada Broods
Different broods have homes in different areas. While this brood known as IX will appear in southwest Virginia, North Carolina and West Virginia, Brood X is scheduled to emerge in the areas of Pennsylvania and Washington D.C. Although the species does not have a destructive nature, young trees and saplings could die because of the egg-laying process. So if you live in the area targeted for the cicada invasion, don’t choose this summer as the time to plant new trees! (1)
