ST. LOUIS – It’s going to get louder in the coming weeks as massive numbers of periodical cicadas are emerging in full force.

We haven’t really been hearing them sing or perform yet so we’re probably just at those very early stages of them just beginning to emerge here in the area,” Dan Zarlenga, media specialist for the Missouri Department of Conservation St. Louis region, said.

Brood 19 is a 13-year periodical cicada that last emerged back in 2011. These emerge earlier than the annual ‘dog day’ cicadas that you hear in July and August.

“The difference is when the periodical cicadas emerge; it’s like quantity over quality or whatever you want to say,” Zarlenga said. “They come out less often, but they come out in huge numbers so they totally overwhelm predators.”

These cicadas spend the majority of their life underground. When they emerge, they’ll climb a tree or other vertical structure, shed their exoskeleton and take about five to seven days to form into adults.

“Once they do that, then they will very quickly start singing and making the sounds that they’re famous for. And what they’re making that sound for, is to attract mates,” he said.

Their sounds late in the spring will be impressive but thankfully, they only sing during the day.

“Millions of them emerge when they’re all calling together; it can be very, very, very loud. You might hear them indoors with all the windows and doors shut. If you go outside, you know people have measured them with decimal meters at 90 to 100 decibels, which is getting close to airplane engine sounds,” Zarlenga said.

While the sound may be an annoyance, they serve an important role in the ecosystem because they’re an abundant food source for many animals.

“So, as a result, this is actually a boom for them. This is actually a lot of nutrition that they’re getting. And sometimes wildlife populations actually show a little bit of a spike after these cicada emergences,” he said.

They are also great bait for fishing.

Once they emerge, we’ll be dealing with them for about six weeks, with the anticipation of being done by the Fourth of July.

“I think what’s really fascinating is we see these winged creatures flying around for about six weeks. But this represents only a very small portion of their life. They’ve spent 13 years underground so if you spent 13 years underground, I guess you’d be entitled to a little time flying around too,” said Zarlenga.