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Order: Homoptera
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Common Name--Cicadas, Leafhoppers,
Aphids, Scale Insects, and
Others
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Names
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The order Homoptera is pronounced "ho-MOP-ter-a". This
scientific name comes from the Greek words "homo", which means
same, and "ptera", which means wings. This name refers to the
fact that the front wings, when present, are uniform in
structure being either membranous or slightly thickened. The order
Homoptera sometimes is included with the true bugs in Hemiptera.
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Homoptera includes cicadas, treehoppers, froghoppers (or
spittlebugs), leafhoppers, planthoppers, whiteflies, aphids
(or plantlice), phylloxerans, and scale insects. Some
leafhoppers with pointed heads are called sharpshooters. Scale
insects that have soft, waxy coverings are called mealy bugs,
and those with hard shells are called armored scales.
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Diversity
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More than 32,000 species of Homoptera are found throughout
the world. Of these, about 4,000 are cicadas, 8,600 are
leafhoppers, and 3,600 are aphids. Many species are yet to be
described and named, especially in tropical regions. There
are almost 6,400 species of Homoptera in the United States
and Canada.
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Habitats
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Members of the order Homoptera are plant feeders and are found
wherever plants grow. Some Homoptera, such as cicadas, live
high in the tops of trees. There are some scale insects that
feed on the roots of plants. Some species can be found in ants
nests or in rotten logs. Many Homoptera are found in greenhouses
or fields where crops are cultivated. There are no Homoptera
that live in water.
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Form and Function
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Adult Homoptera are generally between four one-hundredths and
two inches in length. Some tropical species are more than
four inches long. Homoptera may be hard or soft bodied, and
they may be smooth or covered with hairs or spines. Many
species cover their bodies with waxy secretions, which can form
filaments longer than the insect's body.
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Most Homoptera have two pairs of wings, but some have only one
pair, and some are wingless. The wings usually have a
membranous texture and are held tentlike over the abdomen.
The wings and bodies of most species are green or brown, but
some species have bright colors of red, yellow, blue, and
orange.
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Many Homoptera have common names with "hopper, " such as
leafhopper. These species have hind legs that are adapted for
jumping.
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The Homoptera have piercing and sucking mouthparts that are in
the form of a beak, similar to the Hemiptera. This beak arises
from the hind part of head, which is bent downward. Their
antennae are short and hairlike, but are absent in females of
some scale insects.
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The abdomens of some Homoptera have different structures. The
first segment of the abdomen may have a sound producing organ,
as in cicadas. Aphids have a pair or short tubelike projections
at the back of their abdomens. These structures are called
cornicles and are used for secreting defensive chemicals.
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The scale insects are unusual in that the females do not have
wings and often do not have legs. Males generally have legs,
but they only have one pair of wings, and they lack mouthparts.
The developing nymphs of many scales secrete a waxy covering
that is hard and scalelike or soft and cottony.
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Life Cycle
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The Homoptera generally have incomplete metamorphosis
(egg-nymph-adult). Some Homoptera, such as aphids, do not lay
eggs, but give birth to living young. Whiteflies (family
Aleyrodidae) have a resting stage, similar to a pupa, between
the active nymph and adult stages.
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The cicadas commonly are heard singing in the summertime.
The males produce a loud buzzing noise for attracting mates.
Each species has a different song, as heard in the
Phantastic
songs of the S. E. Asian Cicadas!. After mating, the
eggs are laid in twigs or stems of the plant. After hatching,
the nymphs live underground and feed on roots for several years.
Upon reaching maturity, the nymph emerges from the ground, crawls
up a tree trunk, and sheds its skin, as shown in the video clip
at Iowa State University's
Periodical Cicada Emergence in Iowa in 1997.
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There are two types of cicadas based on their life cycles.
Dog-day cicadas include the black and green species, some of
which appear every summer. Nymphs of dog-day cicadas live
underground for no more than seven years. The periodical cicadas
include three species in northern United States that have 17-year cycles , and three species in southern United States with
13-year cycles. Each of these six species has different broods,
with all in a brood emerging in a given year a some part of
the country.
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Aphids have complex life cycles. Aphids usually spend the
winter in the egg stage. These eggs hatch in the spring into
wingless females. These females produce young without mating,
a form of reproduction known as parthenogenesis.
They also give birth to living nymphs, all of which are females.
After several generations of reproducing by parthenogenesis, a
sexual generation appears that includes males and females.
These males and females mate, and the females lay eggs, which
overwinter.
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Food and Feeding Habits
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All Homoptera feed on the sap of plants with their elongated
beaks. Many species feed only on one species of plant.
Some leafhoppers lay their eggs only on a certain species of
plants, but after hatching, the nymphs will move to many
different host plants for feeding. Some species prefer to
feed on stems, others prefer the leaves, and some prefer the
roots of plants. Several Homoptera make galls on plants and
feed within these enlarged growths.
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The Homoptera must suck large amounts of sap from the plant to
get their nutrients. Much of the sap is sugary water that
cannot be digested. This extra water is passed through their
body and excreted as "honeydew." Ants and other insects "tend"
the Homoptera and collect honeydew for their own food. In
return for their food, ants will protect the Homoptera that
excrete the honeydew. Some ants will build barns of chewed
plant material to enclose their "cows." Other ants will carry
aphids to their nests in the ground to survive the cold winters.
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Natural Enemies
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The insect predators of Homoptera generally feed on the soft,
inactive forms such as aphids and scales. Ladybird beetles,
both larvae and adults, feed on aphids, scales, and other
Homoptera. Larvae of lacewings (Neuroptera) are known as
aphid lions because of their predation on aphids. Photographs of
lacewings can be found at
A Guide to Natural Enemies in North America. Many species of
flower flies (Syrphidae) also have larvae that feed on aphids.
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Among the many wasp enemies, some species of Braconidae are
parasites of aphids. The wasp larva empties the contents of
the aphid's body and emerges from a small hole in the dead
aphid, called a mummy. The large cicada killer, Sphecius
speciosus (Family Sphecidae), provisions its nests with cicadas.
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Olympic Feats and Other Strange Facts
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One aphid and its offspring could produce 1,560,000,000,000,000,000,000,000
individuals if none died during a year. If these were stacked
on top of one another, they would form a tower more than one
mile long, one mile wide, and 62,400 miles high.
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Nearly four tons (7,775 pounds) of aphids have been estimated
to be present in some fields of alfalfa.
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Froghopper nymphs, known as spittlebugs, produce a spittle-like
mass that eventually surrounds them for protection.
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Periodical cicadas are among the longest living insects, with
some living for 17 years. Male cicadas are also the world's
loudest insects.
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The efforts of 150,000 lac insects are required to produce one
pound of lac for making shellac.
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Pit scale insects in the southwestern United States have a waxy
covering over their body that has been used as chewing gum by
Indians.
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The cochineal insects are scale insects that occur in the
southwestern United States and Mexico. The red color of the
scale has been used as a dye for food, lipstick, and many other
items.
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The manna mentioned in the Biblical book of Exodus comes from
the tamarisk manna scale insect, which still occurs in Israel.
The scale insect excretes honeydew that forms sugar-like masses
on the leaves of the host plant.
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Some of the giant scale insects form hard round coverings as
they are developing. These round scales are called ground
pearls and are used as beads in some parts of the world.
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The Chinese wax scale insect, Ericerus pela, secretes a
pure white wax that is used to produce special candles in
China and Japan.
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The Good and The Bad
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Some Homoptera have been beneficial to man. Aphids produce
many offspring that provide food for other insects. Shellac
and varnish have been made from the lac insects, Laccifer
lacca, which occurs in India. Certain scale insects provide
pigments used in the making of dyes. And, of course,
could we enjoy the dog-days of summer without the wondrous
buzzing song of the cicada.
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Many Homoptera are considered harmful because of their feeding
damage that causes plants to wilt or loose their leaves. The
very act of laying eggs can harm the plant and can cause leaves
to curl and brown. Gall forming phylloxerans include pests
of nuts and fruits. Mealybugs and whiteflies are major pests of
plants grown in greenhouses. Some aphids and leafhoppers also
transmit pathogens that cause plant diseases. The honeydew
excreted by Homoptera promotes the growth of mold, which
interferes with plant photosynthesis. Photographs of pest
species and their damage are available at the Virginia Cooperative Extension Web site
Insects That
Feed by Sucking Plant Juices.
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Taxonomy
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Selected Families of North American Homoptera
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Fulgoridae (fulgorid planthoppers)
Acanaloniidae (Acanaloniid planthoppers)
Flatidae (flatid planthoppers)
Cercopidae (spittlebugs, froghoppers)
Cicadidae (cicadas)
Cicadellidae (leafhoppers)
Membracidae (treehoppers)
Psyllidae (jumping plantlice)
Aleyrodidae (whiteflies)
Aphididae (aphids)
Adelgidae (pine and spruce adelgids)
Phylloxeridae (phylloxerids)
Ortheziidae (ensign scales)
Margarodidae (giant scales)
Pseudococcidae (mealybugs)
Coccidae (soft scales)
Dactylopiidae (cochineal scales)
Kermesidae (gall-like scales)
Eriococcidae (felt scales)
Tachardiidae (lac scales)
Asterolecaniidae (pit scales)
Diaspididae (armored scales)
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Selected References
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Borror, D.J. and R.E. White. A Field Guide to the Insects of A
America North of Mexico. Boston: Houghton Mifflin Co.
Arnett, R.H., Jr. American Insects A Handbook of the
Insects of America North of Mexico. New York:
Van Nostrand Reinhold Co.
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Links
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For an extensive list of Homoptera Web sites, go to the
Links Component
of the module.
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Picture Credits
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Dr. Ross E. Hutchins (Deceased)
Mississippi Entomological Museum
A treehopper, Platycotis vittata
A leafhopper, Aulacies irrorata
Wooly aphid with wax filaments
Aphid with cornicles on abdomen
Mealybug scale insect tended by ant
Cicada killer wasp with cicada
Froghopper nymph with spittle
Gall cut open to show phylloxerans
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