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UGA studying 13-year cicadas

Photo by Heather Middleton

Photo by Heather Middleton

By M.J. Subiria Arauz

marauz@news-daily.com

Spring has already sprung, and 13-year cicadas are emerging in the state of Georgia.

The University of Georgia is conducting a study of these insects, which only appear every 13 years, said Nancy Hinkle, a professor of the department of entomology at the university. Local residents who see the insects should take pictures of them and the skins they shed. People can e-mail their pictures to, insects@uga.edu, she said.

"We need to study them now, because they won't be back until 2024," said Hinkle.

She said the university is studying the insects to figure out why they only emerge every 13 years, and how they are able to do it.

Cicadas are not pests, or locusts, said Hinkle. They sip plant sap and don't damage plants.

The insects will come out, mate, lay their eggs and die within a couple of months, she said.

Cicada nymphs derive from the ground by creating small mud chimneys, said Hinkle. The nymphs crawl up on trees, shed their skins and fly to the tree tops, where males call for mates. The females reply with wing clicks, which attract their mates. "This is an adult emergence--the eggs hatched 13 years ago, so these insects just became teenagers and are demonstrating their independence by emerging from the ground," she said.

The females will lay their eggs in slits on twig tips, said Hinkle. This causes the end of the branch to die and fall off--a natural pruning service to prevent breakage in the next winter snowstorm. "This natural pruning prepares the tree to survive snow and ice the following winter without major limb loss," she explained.

When the insects die and their bodies decay, they produce a natural fertilizer for trees and plants, said Hinkle.

"Cicadas can be found in hardwood forests," she said.

She said cicadas are around trees, such as oak trees, pecan trees or any broad-leaf tree.

Hinkle said the 13-year cicadas that are arising belong to Brood XIX, or Brood 19. Insects of the same species are part of a brood, or group number. Scientists designated broods for insects years ago, she said.

"Brood XIX is Georgia's only 13-year cicada," she explained.

Thirteen-year cicadas are also known as periodical cicadas, said Hinkle.

According to Hinkle, other periodical cicadas, include the 17-year cicadas which are also found in the state of Georgia.

She said overall, there are 23 broods of periodical cicadas, which include three different groups for the 13-year cicadas and 20 different groups for the 17-year cicadas.

Periodical cicadas have red eyes and are two-thirds smaller than annual cicadas, which also emerge in Georgia. They come out in the spring and have black bodies and orange-veined wings.

Annual cicadas have black eyes, green bodies and pop out in the summer, she explained. They are expected to emerge in August, she said.

Both the annual and periodical cicadas can sing loudly, but the huge numbers of periodical cicadas may produce a louder sound, said Hinkle. "Only male cicadas sing and they sing during the day," she said. "Their song is referred to as 'The Song of Summer,' because the droning sound is the background music to summer activities," she added.