APRIL 19, 2011 -- You may find yourself yelling at your kids while you're "Sprout and About" this spring, and it won't be because you've lost your cool. The emergence of a periodical cicada may make normal conversation difficult, according to a Missouri Department of Conservation news release.

Missouri is on the verge of a major periodical cicada emergence. Periodical cicadas emerge earlier and are different from the more familiar dog-day cicadas, which come out later in the summer. The periodical varieties have dark bodies and reddish eyes and wings. Dog-day cicadas range from brown to green with black-and-white markings. Periodical cicadas also are noticeably smaller than dog-day cicadas.

Periodical cicadas come in several varieties. Some spend 13 years in the ground feeding on sap from tree roots before emerging en masse. Seventeen-year cicada nymphs take four years longer to mature. To further confuse matters, periodical cicadas exist in broods that inhabit geographic areas ranging from a few thousand square miles to vast chunks of real estate spanning several states.

When a brood emerges, as many as a million noisy male cicadas can gather in trees over a single acre and join in a piercing chorus of mating calls. Their combined voices create an unforgettable din, drowning out lawnmowers and making normal conversation impossible.

Missouri witnessed the emergence of a particularly large brood of 13-year cicadas in 1998, so 2011 promises to be a noisy spring in much of the state. This year's emergence is expected to cover most of Missouri. The Bootheel and part of northwest Missouri will escape the phenomenon. If this disappoints you, cheer up. The existence of multiple broods means you don't actually have to wait 13 or 17 years for the next emergence. Other single-brood emergences are expected in northern Missouri in 2014 and in west-central and southeastern Missouri in 2015.

The cicada chorus is likely to begin tuning up in early May, reach a deafening crescendo in a couple of weeks, and taper off in June. Although periodical cicadas are not much bigger than the end of your pinkie finger, their numbers allow them to drown out a chainsaw.

Male cicadas use a pair of structures called tymbals to produce their song. Tymbals are elastic membranes located just behind cicadas' last pair of legs. Tiny muscles contract and relax rapidly, crumpling the tymbals and letting them snap back into their original shape. They make a loud click with each muscle twitch, creating a high-pitched droning sound. The process is similar to crumpling a soft-drink bottle.

Female cicadas use a sharp appendage to slice into tree twigs, where they lay their eggs. Twigs often die, and sometimes they break and droop. This "flagging" can be quite visible in areas with large numbers of cicadas. The damage to mature trees is minor, so pesticide use is not recommended.

Cheesecloth, mosquito netting or netting with mesh smaller than 1/4-inch is effective for protecting small trees.

A periodical cicada emergence creates a brief food bonanza for birds and fish. It also creates opportunities for anglers. As fish go on feeding binges, anything resembling a cicada can prompt a bite.

When the brood that is emerging in Missouri this year last appeared, it was joined by a large brood of 17-year cicadas. It was the two broods' first joint emergence since 1777. Their respective life cycles dictate that such joint emergences occur every 221 years, so the next one will take place in 2219.

Learn more about the cicada at the Missouri Department of Conservation website.

Photo by Jim Rathert, courtesy of Missouri Department of Conservation

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