CENTRAL OHIO (WCMH) — If you live in southern Delaware or northern Franklin County, you’ve probably heard the distinctive chirping coming from recently emerging 17-year cicadas.

Entomologists call it Brood X. However, their schedule may be off by four years; this cohort last raised a racket in the Columbus area in the late spring of 2004, famously disturbing golfers and fans at that year’s Memorial Tournament at the Muirfield Village Country Club.

The early arrival of Brood X followed the expected 2016 emergence of Brood V observed in eastern Ohio, including Licking County. Brood V has a territory that extends from New York to West Virginia, which is farther east than this year’s Brood X.

Depending on the brood — there are 15 that appear around the country, with varying life cycles — cicadas make noise about once every 17 years during the mating cycle, when the females lay eggs in the ground, only after soil temperatures warm past 64 degrees.

So what’s happening this year?

Ohio State University entomologist Dr. David Shetlar theorizes that persistently warm weather, perhaps due to climate change, is causing this year’s early-emerging cicadas to potentially shift to a 13-year pattern, similar to their southern brethren. This year has been unusually warm: Columbus recorded its warmest February and April on record, going back to 1879.

“Their little genome is saying, ‘Come out now, because it’s time to develop,’ ” Shetlar said.The loud symphony will continue for a few more weeks in parts of Powell, Lewis Center and as far east of Westerville. “We call it chorusing. It’s one of the strategies they have in order to discourage the birds and other animals.”

Shetlar noted that in the coming few weeks the females will lay their eggs near the conclusion of a three-week noise fest, and then it’s all over. He added that the absence of predators scared away by the noise allows the cicadas to prosper during their short time above ground.

So consider the periodical cicadas-the strange-looking black- and red-eyed insects-merely a nuisance as they climb our backyard trees, and then fall back into the grass, but are otherwise harmless-to us and the trees.

Oh, and they are not to be confused with the annual summer cicadas, which are less noisy and appear every mid-summer to serenade us to sleep. Some believe the first frost occurs about 90 days after the dog-day cicadas are heard.