WASHINGTON — Cicadas reached peak numbers last week in and around the D.C. area and are now starting to die at a rapid rate. In some places, they can be smelled as they rot away.

“As we move past the peak, the dead (cicadas) are starting to pile up, returning their nutrients to the soil,” Daniel Gruner, a professor of entomology at the University of Maryland, wrote in an email.

That decay process is producing an odor. “When animals die they have a pretty distinct BAD smell,” wrote Paula Shrewsbury, also a professor of entomology at the University of Maryland, in an email. “As part of the decay process there are a number of interactions between enzymes and microbes that result in the ‘smell of death.’ Cicadas are no different than other animals; when they die they smell bad.

“This smell will continue until the cicadas are dried out and/or decomposed,” she continued. “The upside is that by dying, the cicadas are returning nutrients back in the soil under trees that will support their young for the next 17 years.”

With the numbers of dead cicadas mounting while the chorusing of the ones still alive becomes fainter as the days pass, when will they be gone entirely?

“From past cycles, broods last about 4-6 weeks from their first emergence,” Gruner wrote. “We are about one month in, and we see they are diminishing. I do expect they will be largely gone in 1-2 weeks. I will mourn their passing.”

Gruner said he expects the cicadas to hang around longest in cooler areas west of Washington, such as Leesburg, Va., and Winchester, W.Va., where they were last to arrive.

Shrewsbury agreed. “Since the length of the life cycle of adult cicadas should be more or less the same, areas where cicadas emerged later should have adult cicada activity later,” she wrote.

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