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Periodic cicada emergence will include western Missouri
Kansas City, Mo. –
For 17 years a particular brood of cicada nymphs tunneled through the soil,
sucked sap from roots and grew from ant-like specks into bumblebee-sized nymphs.
They will emerge by the thousands this spring in western Missouri and transform
into winged adult insects, with male cicadas raising a raspy racket as they serenade
females.
Periodical cicadas pose no threat to people
and minimal threats to trees. But early summer will be abuzz with sound where 17-year
cicadas emerge, said Rob Lawrence, forest entomologist for the Missouri
Department of Conservation (MDC).
“In some places
they make a pretty loud noise,” Lawrence said.
The cicadas will
begin emerging from the soil in early to mid-May, depending on how quickly
weather conditions warm soil temperature. Current conditions could prompt the
emergence to begin May 10 to May 12 in the Kansas City and St. Joseph areas, he
said, though warm temperatures could hasten emergence.
Cicada nymphs will open half-inch holes in the
soil surface as they emerge. Some may build three- to five-inch tall mud chimneys
above their holes. Wingless nymphs will climb up on trees and other objects,
shed their exoskeletons, and become adults with wings. That leaves brownish
paper shells that resemble shed skins attached to trees, porches and posts.
Adults will
climb or fly into trees. Males will join together to form choruses to attract
females. Or consider it a jam session with instruments. Male cicadas rapidly flex two drum-like
structures in their abdomens called tymbals. The flexing produces a click, and
the clicks come so fast it produces a raspy hum. They sing during the day with the loudest drone rising during the hottest part of the day.
Annual cicadas
appear each year and their drone ebbs and flows in the tree tops. But annual cicadas appear later in the summer than the periodical
variety, Lawrence said. Periodical cicadas will be prevalent in late May and
June, annual cicadas appear in July and August.
Periodical
cicadas are so named because the broods emerge in 13-year or 17-year cycles. This
17-year brood emergence is occurring in an area that extends from Iowa to Texas
and includes western Missouri and eastern Kansas. A 13-year emergence is also occurring in
southeast Missouri and portions of other states. But the two broods are not
expected to overlap.
Striking red
eyes and blackish bodies distinguish periodical cicadas. Annual cicadas have
greenish bodies, dark eyes and are about two inches long. Periodical cicadas
are slightly smaller. Both types of cicadas include various species.
Periodical
cicadas will not appear in all locations within the brood emergence area,
Lawrence said. A field or yard that did not have trees 17 years ago, or perhaps even 34
years ago, would not have provided a place for females to lay eggs and for the
nymphs to hatch and drop to the soil. Also, soil condition changes such as
severe drought or construction disturbance could reduce the number of nymphs.
However, in some
areas with favorable conditions, periodical cicadas could appear by the
hundreds or even thousands. Such large, periodic emergences provide a feast for
creatures that feed on insects. Wild turkeys will eat nymphs, so will fish
where cicadas drop into the water. The large emergences are an
evolutionary adaptation that lets the species survive by overwhelming predators
with sheer numbers and a lengthy emergence cycle, Lawrence said.
Cicadas can
affect trees. Females cut narrow slits in small branches and lay eggs in the
slits. This can cause stress for limbs. Large, mature trees are generally not
greatly affected. Although homeowners may notice some browned and broken branch
tips, which is called flagging. Young trees can be harmed, and fruit trees can
be stressed, because they have small branches favored by females for egg
laying.
MDC foresters do
not recommend using insecticides for cicadas. Small or newly-planted trees and
shrubs can be covered with mesh and tied at the trunk. To reduce stress issues,
homeowners should water young trees well during summer’s hot and dry months,
Lawrence said.
Back in 1998, when the parents of this
17-year cicada brood were mating, an adjancent 13-year brood also emerged. But that
overlap only occurs once every 221 years, Lawrence said.
This emergence
will not be as large but will still be noisy. Adults emerging from the nymph
shells will be soft at first. But within hours their wings and exoskeleton will
dry and harden. They will then begin making the next generation that will sing
in 2032.
“Once they get
out, they’ll be singing in the trees for a while and make the racket,” Lawrence
said.
For more
information on periodical cicadas, visit mdc.mo.gov/node/12097 or www.magicicada.org.
Video from a 2011 periodic cicada emergence in central Missouri is available at
http://www.youtube.com/watch?v=Ve3NvNy17yk.
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