Insects emerge from 17-year slumber to invade US

After a 17-year nap, trillions of red-eyed insects are crawling their way above ground in 14 US states and the US capital.

Loudmouthed and ugly, the cicadas will fly clumsily into pets, bushes and unwitting pedestrians as they engage in a frenetic mating ritual that lasts well into June. Then they’ll disappear for another 17 years.

Keith Clay, a biologist and cicada researcher, said the appearance of cicadas is “an amazing biological phenomenon”.

The one-and-a-half inch-long black bugs with iridescent wings buzz around, but are basically harmless. They don’t bite and they don’t sting. They live above ground as adults for about two-and-half weeks to reproduce all they can before dying.

The adult males begin the mating ritual with a long buzzing sound that attracts the females.

The chorus from one colony’s male insects is so loud that the insects can drown out outdoor events.

Scientists say this year’s batch, the largest of the cicada groups that appear at various intervals, offers researchers a rare opportunity to study the insect’s impact on the nation’s forests.

Recent studies indicate cicadas are growing in numbers due in part to deforestation.

Cicadas tend to thrive in sunlit forest edges, which often provide the warmer weather and younger trees most ideal for them to lay their young. That’s because younger tree roots can sustain the 17-year feeding cycle of nymphic cicadas until they mature.

There are more than a dozen broods of 17-year cicadas, along with several 13-year varieties. This year’s group, Brood X, is the largest and is concentrated in the midwest and the mid-Atlantic.

Found only in the United States east of the Great Plains, the periodical cicadas burrow into the ground after hatching, some digging as far as eight feet under.

Below the earth, the nymphs slowly suck the sap from tree roots for nourishment. After 17 years, they emerge and climb trees and shrubs, where they shed their crunchy skins and harden into maturity.

The insects are a treat for robins and other birds, and even some pets, who are at risk of diarrhoea or constipation if they eat too many.

Once the bugs mate, the females cut slits into tree branches, where they deposit 400 to 600 eggs.The eggs hatch in a few weeks and the young cicadas dig into the ground and won’t emerge until 2021.

More in this section


Select your favourite newsletters and get the best of Irish Examiner delivered to your inbox