FILE - A mature cicada dries its wings on a blueberry tree in Fairfax, Virginia. (Photo: Diaa Bekheet)
FILE - A mature cicada dries its wings on a blueberry tree in Fairfax, Virginia. (Photo: Diaa Bekheet)

In a matter of days, billions of cicadas — 3-centimeter, winged insects that buzz loudly while seeking a mate — will emerge from the ground in at least 15 U.S. states from the Midwest to the East Coast, insect specialists say.

They are known to scientists as Brood X (Roman numeral 10) periodic cicadas. Entomologists say periodic cicadas are unique to the United States. And while there are many broods of periodic cicadas that appear on rigid 13- and 17-year schedules in different years, Brood X is one of the largest and most noticeable.

The scientists say the insects lay dormant, feeding on tree roots and slowly growing underground. On the 17th year of their cycle, when the ground temperature reaches the right temperature, they emerge en masse. Scientists say in the regions where cicadas are found, there may be as many as 1 to 1.5 million of the insects per half-hectare.

Scientists say the mass emergence is key to the insects’ survival — there are too many for predators to eat all of them — and it usually happens at dusk. Once out of the ground, the cicadas molt and wait for their bodies to dry and harden, then they fly to the tops of trees where they feed and look for a mate, which they do by making a loud buzz.

Experts say that when huge groups of cicadas are buzzing, the sound can be deafening — as loud as 95 to more than 100 decibels, comparable to a motorcycle at full throttle. 

But beyond the noise, scientists are quick to note that the insects are harmless. They do not destroy crops or bite humans, and they are active for only about four weeks. Scientists say the biggest nuisance caused by the cicadas is when they die and their carcasses fall to the ground, often attracting vermin. 

Scientists say as the weather continues to warm in the Eastern and Central U.S., the mass emergence of the cicadas could come any day.