Periodical Cicadas
Periodical cicadas will emerge this year throughout most of the southern
two-thirds of the state. Emergence should begin in early June and last
about three weeks. Outside Illinois, this emergence of the Great Southern
Brood will cover most of Missouri, western Kentucky and much of the
southeastern United States, north of Florida and south of Kentucky and
Virginia. Very small trees may be subject to heavy damage by this insect’s
egg-laying activities.
Periodical cicadas occur in most areas of the eastern half of the United
States. In the northern half of the country, these insects have a 17-year
life cycle; those in the southern half have a 13-year life cycle. Rumors
floating around the state suggests that 13- and 17-year emergences will
coincide this year, which would cause very heavy damage. Let’s
set the record straight. First, only a single brood of 13-year cicadas
is expected to emerge this year. Also, there is apparently only one
region in North America where 13 and 17 year broods emerge in the same
area and this is in a small area near Clinton, Illinois.
Nymphs that hatch from eggs inserted into stems drop to the ground,
burrow into the soil and find a root to feed upon. The nymphs suck sap
from the roots until the last year of their life cycle, when they emerge
from the soil in the late spring, climb a tree and emerge as adults.
The adults are black, about 1 1/4 inches long and have red eyes. They
have clear wings with orange veins. The adults do little feeding, spending
most of the daylight hours involved in reproductive activities. Male
cicadas sing during the day to attract females. Mated females select
twigs and branches up to one inch or more in diameter and insert their
eggs into slits made with their ovipositors. Very little egg-laying
occurs in the first ten days after emergence. Eggs are laid mostly during
the last ten days of the female cicada’s adult life.
We anticipate emergence of the 13 year cicadas this year from Hancock
and eastern McDonough counties south to Morgan, Sangamon and Macon counties
and also from Ford, southern Livingston and western Iroquois counties
south. The rest of southern Illinois is included in this 13 year brood
emergence, except Iroquois, Vermilion, Edgar, Clark, Crawford, Lawrence
and Wabash counties on the east and Alexander, Pulaski, Massac, Union,
Jackson, Perry and southern Randolph counties in southern Illinois.
Periodical cicadas are a threat to small trees with trunk diameters
of two inches and smaller. Their egg-laying may cause trunks and branches
to snap off in windy conditions. Avoid planting very small trees before
an emergence in areas where cicadas are likely to appear. Realize, though,
that even in the regions listed above, some areas will have few cicadas
or none at all. If an area has been cleared of trees and shrubs within
the last few hundred years or was originally prairie, periodical cicadas
are unlikely to be present. These insects do not fly very far from where
they emerge. That fact, combined with their long generation times, means
that the spread of periodical cicadas is very slow.
Insecticides are only marginally effective against cicada. Young trees
with small trunks should be protected with hardware cloth, screening
or tree wrap during the few weeks that the adult periodical cicadas
are present.
Early Summer 1998
Vacations and the Yard &
Garden | Periodical Cicadas
| Bronze Birch Borer
| Moss Problems in Lawns
| Bug Bites—Grubs Are
Coming to Your Lawn! | Lawn
Care Calendar | Cybergarden
Sites | Hort Shorts
| Hort Tips | Food
Handling: Picnics, Barbecues and Outdoor Eating | In
the Kitchen: Persuading the Public | Locally
Grown: A Kitchen Herb Garden | Health
Update: Gardening in the Summer Sun
Index
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