The recent emergence of millions of cicadas in central and south-central Connecticut after living underground for 17 years got me wondering about any possible damage to the trees where they are busily nesting.
Don't worry, says Chris Maier, an entomologist with the Connecticut Agricultural Experiment Station who has studied cicadas for many years. "I've never heard of a tree being killed by them."
His best advice: "Don't overreact if you see a few. Enjoy the wonderful insect -- only one shot in 17 years."
Periodical cicadas -- the species in Connecticut is Magicicada septendecim -- have to make it snappy to reproduce during their brief adulthood of just two or three weeks. The adult males attract mates by singing -- actually vibrating a pair of ribbed membranes at the base of their abdomens at a rather amazing decibel level -- and after mating, the females carve slit-like cavities in pencil-sized tree branches where they deposit the eggs -- 30 to 40 in each nest.
"They prefer deciduous trees," Chris says, "but they will occasionally lay eggs in shrubs," provided they have woody stems. It's probably safe to say that cicadas avoid all confers, he adds.
Oaks, hickories and apple trees are among the trees where they lay lots of eggs.
Cicadas can be a bother for fruit growers, who report that they sometimes see changes in the growth of apple and peach trees, Chris says, and a young tree with only a few branches can be disfigured.
"But it's got to be near a forest. [Cicadas are] basically a forest animal, but they do extremely well and spread into apple orchards where apple orchards and forests meet one another."
And, he emphasizes, "I would never recommend pesticides."
Cicadas are very localized and are unlikely to drift any significant distance from their range from 17 years ago, Chris says. His article, "Return of the Periodical Cicadas," includes a map of the 20 towns in Connecticut where cicadas emerged in 1996 -- as far north as Farmington down through Southington, Cheshire, Hamden and Meriden to North Haven, and through New Britain, Bristol, Middletown and Durham, and along the coast up to Madison.
The cicadas are now rapidly moving high up into the treetops, and on sunny days the chorusing is "incredibly loud," Chris says. They tend to stay in the same forest, and some of the smaller populations have disappeared.
The "real concentrations" are in the traprock ridges that band the state, such as those one sees from the interstate. Hamden, southern Cheshire, Berlin and Southington have many large populations, as do the Hanging Hills area of Meriden and the Ragged Mountain area west of New Britain. There also are smaller populations around Sleeping Giant State Park, Chris says.
If your trees happen to be in an area where the cicadas are plentiful, Sharon M. Douglas, plant pathologist with the agricultural experiment station, has several common-sense suggestions.
Help the overall vigor of your trees by maintaining adequate soil moisture and mulching, "since a vigorous plant will be much more responsive, both biochemically and physically, to walling off and reatcing to the damage caused by egg-laying."
If young twigs are damaged, Sharon says, the best way to handle the flagged twigs is to prune them.
"Some of the damaged twigs will 'prune' themselves, although a good, clean pruning cut will be better for callus formation," she says.
Any damage will be more serious on young trees, Sharon adds. "Damage to mature trees is usually inconsequential."
A wonder of nature with its bright red eyes and 17-year reproductive cycle, a cicada, top, rests on a branch in Meriden. File photo by JOHN WOIKE | The Hartford Courant.
An adult female cicada, about 1 1/2 inches long from the front of the head to the tip of the wings, has inserted her black ovipositor (on the underside of the abdomen) into a cavity in a slender tree branch to deposit 30 to 40 eggs. Photo by Chris T. Maier.
