May 2, 2008

For 17 years, periodical cicadas have been feeding and maturing in silent darkness, but in May they’ll emerge into the light and begin a mating ritual that will have many Kentuckians reaching for ear plugs.

Brood XIV, the identifying name for this particular cluster of cicadas, will begin surfacing during the first week of May in southern Kentucky counties, with others of the brood progressively appearing further north as the soil temperature rises.

“This year is really a special year for Kentucky because we have an emergence that’s going to occur over most of the state,” said Ric Bessin, University of Kentucky entomologist, as he traced an invisible line on a map from just west of Owensboro to just east of Hopkinsville. “Everything to the east of that will have cicadas in those counties, so it’s about 80 percent of the state.”

Louisville experienced an emergence of periodical cicadas a few years back. That was Brood X, which was not a large emergence within the state and affected only limited areas. Brood XIV will be much larger in scope.

Bessin said that of the 30 distinct broods of periodical cicadas in North America, approximately a dozen are major emergences where large numbers of the insects come out over many counties. This year’s Brood XIV is one of those.

There are several misconceptions attached to the periodical cicada. For instance, this cicada is different from the cicada that is seen each summer in Kentucky. That one is the dog-day cicada, called jarflies by some people. The dog-day cicada is larger and has a brownish-green hue. The periodical cicada is more streamlined and is black with a number of red markings, including unmistakable bright red eyes. Periodical cicadas are only seen for four to six weeks beginning in May, while the dog day cicada appears in the dog days of summer, July and August.

The periodical cicada is also not a locust despite the fact that many people call them 17-year locusts. Locusts are grasshoppers.

“This misconception probably started with the early settlers,” Bessin said. “They saw these very intense outbreaks of periodical cicadas, and they didn’t know what they were. So they related them back to stories of locust plagues in the Bible. But this is a very different insect. This is a New World insect. These emergences are nothing that the pioneers would have had experience with in the Old World.”

Unlike grasshoppers, cicadas fly for only short distances and don’t swarm, though they congregate in very large numbers in trees. It is not unheard of to have tens of thousands in a very large tree or cluster of trees, he said. And once clustered with their kind, the courtship begins. In their short adult lifespan, cicadas are driven to do one thing: procreate. Males produce a high-pitched whining sound during daylight hours to attract a female. While one male may not produce much sound, 10,000 males do. The result is a very distinctive droning sound that can rise to an earsplitting level.

Doug McLaren, UK Cooperative Extension forestry specialist, remembers that sound well.

“I know that 17 years ago, just talking to someone in a woodland area, you had to be very close to be able to hear one another because of the intense noise that these things put out,” he said.

Woodlands are where periodical cicadas gather because their entire life span is connected to trees. The female lays her eggs at the ends of branches, because her sword like ovipositor, or egg layer, more easily pierces the younger, softer wood. She saws slits into the wood parallel to the branch and deposits about a dozen eggs into each wound. About a month later, the eggs will hatch and the nymphs will drop to the soil where they burrow underground. For the next 17 years the walnut-sized nymphs will feed on the sap from tree roots. Nearly two decades later, they emerge from the ground as adults and begin the cycle again.

Despite their numbers, periodical cicadas don’t do serious damage to established trees. However, what damage there is will be very noticeable by summer’s end, McLaren said.

“Basically by making slits all the way around a branch, the female is girdling that branch. And girdling is nothing more than killing all the life support system that would carry nutrients onto those leaves,” he said. “The ends of all those branches are going to die, so if you get yourself into a position where you can look over the landscape, you’re going to see a brown hue against the green backdrop.”

However, he said, people should not be concerned about this.

“This is one thing the forest community doesn’t have to worry about because it is only going to kill the last three feet of the branches. Next year the tree will simply pick up and start growing again.”

Bessin said the only concern for homeowners might be for the freshly planted young tree. In that case, wrapping the immature tree in netting, or simply waiting until the fall to plant it, will take care of any problems the insects might create.

Though this brood will cover much of the state, not everyone will see them. According to Bessin, counties will experience hot spots with a great many insects and other areas where there are few or none.

“Obviously, if there’s a lot of open cropland with row crops, that’s not good country for cicadas,” he said. “New subdivisions that have been cleared of trees in the last 20 years are not good places for cicadas to emerge. But people who live in wooded areas are very likely to see cicadas for that four to six week period.

“Anyone under 17 years of age is likely to have never experienced cicadas in Kentucky,” he said. “It’s a great opportunity to take kids out and let them experience one of the more unusual things that occurs naturally.”

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