Cicadas

In the past few weeks many clients have been pulling me aside and asking,
"What can I do to prevent damage caused by cicadas?" And, "Are there really cicadas coming?"
The best place to turn for answers is to the great folks at the TN Agriculture Extension Service. And according to them, the 13-year cicada is expected to emerge from soils across much of Tennessee soon.

Millions of 13-year cicadas are expected to emerge from the soils across the state this spring. Female cicadas can damage young trees when they cut slits in twigs to lay eggs

Sometime this spring, when soil temperatures reach about 67 degrees at a depth of 4 inches, large numbers – millions – of cicadas are expected to emerge from the soils of more than one-third of the state's 95 counties. The greatest population concentrations are expected to be in Middle Tennessee.
 
The target date is early May, and four or five days after they emerge, the adult males will start “singing” says University of Tennessee Extension entomologist Dr. Frank Hale. “In some locales, the sound may seem deafening.”


Hale says the high-pitched, shrill-sounding songs of the males may be distracting or irritating, but it’s the activities of the females that can cause damage to the landscape, especially young trees. “After the males attract females with their song, mating occurs and females begin laying eggs inside the branches of woody plants. A female cicada has a knife-like ovipositor that she uses to slit twigs before she lays eggs inside the slits,” he said.
“A single female cicada can lay anywhere from 24 to 28 eggs in each slit she cuts, and she can cut anywhere from 5 to 20 slits in a single twig.” Hale explains that each female can lay a total of 400 to 600 eggs and that the egg punctures pose a threat to young trees.

“Apple, pear, dogwood, oak and hickory are their favorite hosts, but you can see the puncture marks on many tree species,” Hale says. “The punctures can damage young transplanted trees in nurseries and orchards causing the twig tips to wilt and die.”

In areas having a previous history of high populations of periodicals cicadas, Hale says certain preventative measures should be followed. “Delay pruning young fruit trees until after cicada emergence so damaged branches can be removed and a proper scaffolding of branches can be established. When feasible, small, valuable shrubs and trees may be covered with a loose woven or spun fabric such as cheesecloth or floating row cover for protection while cicadas are present.” Hale says insecticides have not proven to be effective for preventing cicada egg-laying damage.

Cicadas cannot sting, and adult cicadas live for only four to five weeks. Eggs hatch six to seven weeks after they are laid and the newly-hatched nymphs (which are white and ant-like in appearance) drop to the ground and work their way into the soil. Nymphs grow slowly and they feed on sap from roots until the spring of their 13th year, when they emerge to start the cycle again.