[Note] This article about the
Science in the News Exhibit case and cicadas in general
was written for an in-house Smithsonian Institution, Staff
By Michael Lipske
Special to The Torch
will be love songs in the air inside the Natural History
Museum this spring and summer-ballads and standards to
make the heart flutter, if you are a cicada.
"We have a whole CD of recorded cicada sounds," museum
Exhibit Writer Sarah Grusin says happily. With 51 tracks
of pure cicada gold to choose from, Grusin plans to have
insect-courting music playing as a backdrop to a new display
she is preparing on the reappearance of the 17-year cicada
in the Washington, D.C., area.
"We're going to call it 'Treetop Opera,'" Grusin says of
the display, located on the museum's first floor. The small
exhibit is a nod to the year's big insect news.
Starting in mid-May, billions of cicadas will begin crawling
out of the ground across the Washington, D.C., area. During
the following weeks, the insects will molt, climb into trees
and, in the case of male cicadas, blast out the loud droning
that is the cicada seduction song.
But it's not just any cicadas the museum is celebrating.
This year marks the return of Brood X. Spawned in 1987, the
nymphs of Brood X have spent 17 years underground, feeding
on fluids from the roots of trees.
Years ago, a U.S. Department of Agriculture scientist started
the practice of using Roman numerals to identify different
broods of the insects called periodical cicadas; each brood
consists of a cohort of cicadas, all of the same age and
thus isolated from other broods by time. Twenty different
cicada broods are known to exist in eastern North America.
Each emerges like clockwork in different years.
Scientists theorize that the long period between emergences
helps confuse unsuspecting predators, most of whom do not
live as long as the cicada and, therefore, have never seen
one. Whatever the reason, "It's worked for millions of years," says
Nathan Erwin, director of the museum's Insect Zoo. "For them,
it's a great way of making a living. If they can mate and
pass their genes on, then 'bingo!'"
The cicada exhibit was Erwin's idea. (Sarah Grusin says
she was on a coffeebreak when "Nate came along and said, 'The
cicadas are coming.'") The intrepid entomologist has not
only eaten cicadas-"they have a bit of a nutty taste"-but
also spent several nights 17 years ago photographing and
marveling at the emerging representatives of Brood X.
"It's an amazing natural phenomenon," Erwin says. "Just the
sheer numbers of them. There have been estimates of a million
per hectare [about 2.5 acres]." And those numbers result in "this
incredible sound," as courting male cicadas commence their
In the display case, an enlarged model of a cicada will
show the drum-shaped organs, called tymbals, males use to
create their mating calls, which vary from species to species.
Three species of cicadas belong to Brood X.
Cicada specimens from MNH's collection also will be on display,
along with information on how the insects while away their
17 years below ground and their few weeks of treetop courting
The exhibit will include a photo and short biography of
the late Richard Froeschner, a former MNH entomologist, whose
frequent lectures on periodical cicadas earned him the nickname
Lately, the job of responding to the public's questions
and worries about periodical cicada invasions has fallen
to Gary Hevel, public information officer with the museum's
Department of Entomology. Hevel tells people that, despite
the mind-boggling numbers that will make up Brood X and the
correspondingly loud racket from the males, cicadas are harmless. "They
don't bite or sting," he says.
Female cicadas scratch slices into thin tree branches while
laying their hundreds of eggs; as a result, trees start dropping
twigs by the end of cicada season. The young cicadas hatch
from their eggs and fall to the ground either in the twig
or take a "swan dive" to the ground, where they burrow, Hevel
says. The tree "pruning" by cicadas won't hurt large trees,
Hevel adds, but "people may want to put cheesecloth over
saplings to keep cicadas away."
In addition to gardeners, Hevel has been hearing from people
worried about Brood X's impact on May and June weddings.
If you shudder at the thought of airborne cicadas crashing
into guests or splashing into punchbowls, he suggests celebrating
the wedding indoors. On the other hand, Hevel says, some
brides and grooms probably will accept Brood X members as
uninvited but memorable guests. Although even Hevel, a confirmed
cicada admirer, admits that the background din from singing
males "might be a problem for hearing the wedding couple
say 'I do.'"
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