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 On
warm evenings, the cicada nymphs emerge from the ground and
crawl a short distance to the closest tree or vertical surface
over a period of a few hours. The nymph's "skin," or exoskeleton,
splits along the top of the head and back of the thorax, and
the adult begins to emerge.
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Under the cover of darkness, the adult maneuvers out of the
nymphal "skin." The white color means the cicada is still soft
and prone to drying out. At this stage, the adult can only
move slowly, making it very vulnerable to predators. |
Over several hours, the adult cicada pumps "blood" or hemolymph
from its abdomen into its wing veins --- expanding the folded
wings . |
Most adults hang from the nymphal "skin" or exoskeleton while
they pump fluids from their abdomen and their exoskeleton hardens
and then turns black. |
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Male
cicadas call from trees. Each individual male tries to call
louder than the next in order to convince females to chose
them for mating.
The
sound is made with structures known as tymbals which are located on the sides
of the first abdominal segment, near the top just behind where the hindwings
attach. Large muscles contract, causing the tymbal surface to bend inwards
which produces a vibrating click. These vibrating clicking
noises are enhanced by a large air chamber that extends well
into the abdomen. Repeated contractions by thousands of cicadas
can create a spectacular din. Females chose the male that
interests them with a flick of their wings which stimulates the male to come
closer.
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After mating, the female deposits her eggs in the treetops.
Look for her ovipositor stuck into the twig. To her right there
are two other wounds in the twig where she laid eggs.
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Two adult cicadas (male on left) mate on a branch. Firmly
anchored to the twig with their legs and mouthparts, the
coupling lasts at least an hour. These adults may also
be feeding.
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Cicadas do not bite or sting. |
A female lays up to 600 eggs in several different slits she
makes in treetop twigs. Four to six weeks later, the tiny hatchlings
float down to the ground. Branch tips at the tops of the trees
die off from the female's egg laying activities. Only two percent
of the hatchlings survive. |
The nymphal "shells" collect
at the base of the tree after the adult cicadas have molted
out and flown up to the tree tops.
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The tips of trees turn brown after the cicada females lay their
eggs in the new growth. It does not damage most trees, in fact
it has a natural pruning effect on most large trees.
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