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University
of Rhode Island GreenShare Factsheets
Cicadas Homoptera:
Cicadidae
Periodical cicadas
emerge in specific locations once every 17 years in the northern
part of their range, and once
every 13 years in the southern part. Different "broods" emerge
somewhere in the eastern United States almost every spring. Massive
brood
emergence is believed to overwhelm predators, which are mostly
birds. This ensures that enough survivors will be left behind to
reproduce.
Male cicadas are capable of making a loud buzzing noise and squawk
when disturbed. The males often synchronize their buzzing in trees
which produces a deafening noise. It is believed that such droning
and squawking is effective in deterring predators. Cicadas do not
bite or sting and have no known toxic chemicals. Adult cicadas
are
usually a nuisance due to their sheer numbers and loud, piercing
call. Adult periodical cicadas, Magicicada septendecium,
are sucking insects, about 40 mm (1.5 inches) long, which appear
from May through July. They are most numerous in the last two weeks
of May and first week of June. They are black and have reddish-orange
eyes and legs. Adults have clear wings with orange veins that are
held roof-like over their bodies. The "dog-day" or
annual cicadas (Tibicen
spp.) appear during the long summer days of July and August. These
cicadas have two-to five-year life cycles, but their broods overlap
and some appear every summer. Dog-day cicadas are larger than periodical
cicadas and have green to brown bodies with black markings and a
whitish bloom. Their wings have green veins. Damage: Annual cicadas do
not ordinarily cause much damage. Periodical cicadas damage
trees above and below ground.
The most obvious damage is that caused by egg laying in small twigs.
This damage causes twigs to split, wither, and die, causing
a symptom
called "flagging." Flagging is especially serious on young plants
(four years or younger) because more of the branches are of the
preferred size for oviposition, 6 to 12 mm (1/4 to 1/2 inch) in
diameter. Some of the more favored trees for oviposition include
maple, oak, hickory, beech, ash, dogwood, hawthorn, magnolia, willow,
apple, peach, cherry and pear. Flowers, vines and shrubs include:
Rose of Sharon, rose, raspberry, grape, black-eyed Susan, hollies,
spirea, rhododendron, viburnum, junipers, and arborvitae. More
than
270 species of plants have been noted as hosts for egg laying female
cicadas. Damage is also done by the nymphs that suck sap from roots.
Prolonged feeding by nymphs on a tree's root system may reduce
plant
growth and fruit production. Immature periodical cicadas (nymphs) develop
underground and suck juices from plant roots. After 13 or 17 years
below ground, mature nymphs emerge from the soil at night and climb
onto nearby vegetation or any vertical surface. They then molt into
winged adults. Their shed outer skins or exoskeletons are found
attached to tree trunks and twigs. The emergence is often tightly
synchronized, with most nymphs appearing within a few nights. Adult
cicadas live for only two to four weeks. During this short time,
they feed relatively little. Male cicadas sing by vibrating membranes
on the underside of the first abdominal segment. Male courtship
songs attract females for mating. Females are silent. After mating,
females lay their eggs in twigs 6 to 12 mm (1/4 to 1/2 inch) in
diameter. The female's ovipositor slices into the wood and deposits
the eggs. One to several dozen eggs can be laid in one branch, with
up to 400 eggs laid by each female in 40 to 50 sites. Cicada eggs remain in the twigs for 6 to 10
weeks before hatching. The newly-hatched, ant-like nymphs fall to
the ground where they burrow 15 to 45 cm 6 to 18 inches) underground
to feed. During the spring of the emergence year, periodical
cicada nymphs may build mud tubes which project three to five inches
above the soil, apparently to escape wet or saturated soils. These
tubes are often mistaken for the tubes that crayfish build. Annual cicadas usually emerge from June through
August. Their emergence is scattered over this time and they rarely
emerge in noticeable numbers. Annual cicada males also sing to attract
females. The cicada killer wasp often captures these insects to
provision its nest in the ground. We do not have problems with periodical cicadas in Rhode Island
and since dog-day cicadas seldom, if ever, cause damage, cicada
control is unwarranted in this state.
Adapted
fromthe Ohio State University Extension, 1999
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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