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Cicadas are sometimes called harvest-flies, dogday cicadas,
or "locusts" (real locusts are Old World grasshoppers). They are medium
to large insects with long, lacy transparent wings that are held peaked over
the body at rest. Their antennae are short bristles.
The harvest-fly or dogday cicadas (Tibicen sp.) are large, stout, dark
insects with lighter markings and greenish margins on the wings. The dogday
cicadas are up to 2 inches long, including the wings. At least seven species
of Tibicen are found in North Carolina. One species of Cicada
and one species of the petit Cicadetta also occur here.
The dogday cicadas or harvest-lies appear during the long summer days of July
and August. These cicadas have 2 to 5 year cycles, but their broods overlap
and some appear every summer. Dogday cicadas are larger than periodical cicadas
and have brown-black bodies with whitish bloom and green wing margins. Annual
cicadas do not ordinarily cause much damage.
There are six species of periodical cicadas (Magicicada). Immature periodical
cicadas (nymphs) develop underground, and suck juices from plant roots. Three
species of periodical cicadas emerge every 13 years, and three emerge every
17 years. Different groups called "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. Adult periodical cicadas live for only two
to four weeks, and during this short time they feed relatively little.
Life Cycle
After 2 or 13 or 17 years below the ground, in May or early June the mature
nymphs bore to the surface, and sometimes even construct mud "chimneys"
up to 3 inches tall. They climb onto nearby vegetation or any vertical surface.
They then molt into winged adults. Their shredded outer skins or "exoskeletons"
are frequently found attached to tree trunks and twigs. Their emergence is often
tightly synchronized, with most nymphs appearing within a few nights.
The periodical cicadas are all similar in appearance; 1 to 1.5 inches long
including the wings. The eyes, legs and margins of the wings are orange. Periodical
cicadas sing and fly in spring, whereas other species of cicadas usually sing
and fly during the summer.
Male cicadas begin to sing with a shrill, loud buzzing noise to attract females.
Females are silent. Male cicadas sing by vibrating membranes on the underside
of the first abdominal segment. Male cicadas are also capable of making a loud
squawk when disturbed. It is believed that such droning and squawking may be
effective in deterring predators.
The male's courtship songs attract females for mating. After mating, females
use their saw-like ovipositors to split open the bark of hardwood trigs and
insert eggs in two rows. They lay their eggs in twigs 1/4 to 1/2 inch in diameter.
One to several dozen eggs can be laid in one branch, with up to 400 eggs being
laid by each female in 40 to 50 sites. Cicada eggs remain in the twigs for 6
to 10 weeks before hatching.
After the eggs hatch, the tiny ant-like first stage nymphs drop to the soil
to borrow in 6 to 18 inches underground to feed for the next 2 or more years.
(Periodical cicadas develop for 13 to 17 years). The nymphs feed on the roots
of many kinds of trees.
Farming and urbanization of suitable habitats have reduced the populations
of many cicadas, and it is thought that some broods fo the 13 and 17 year cicadas
may be extinct.
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Cicadas
Marie Mellinger
The voice of summer is epitomized in the call of the cicada, a long, prolonged
buzzing sound. Yet cicadas have no vocal chords. The Cicada song, which is "sung"
only by the male, is produced when he vibrates a pair of sound chambers that
are located at the base of the abdomen. However, it has often been described:
"they make the sound by rubbing their wings together".
Cicadas begin to sing when the temperature reaches a certain level, usually
around 70 degrees Fahrenheit. If you hear the singers early, it is bound to
be a hot day. Edwin Way Teale wrote: "Cicadas are intoxicated by the heat,
shrilling away through the daylight hours".
They are a common insect; too common in some areas, where they are considered
pests. Yet as part of the natural food chain, cicadas provide food for birds
and animals.
"If Cicadas sing in early morn, it is good for growing corn;
if Cicadas sing all day, it is time to gather hay;
if Cicadas sing at noon, it will be hot enough to swoon."
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