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Arthropoda
- Insecta HEMIPTERA True
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[Also See: Hemiptera Family Key] GENERAL CHARACTERISTICS OF THE HEMIPTERA In this group of abundant species
many cause damage to plants, while others are predatory on harmful
insects. Two families, Cimicidae & Reduviidae)
have species that cause injury to humans by their blood sucking habit or as
intermediate hosts of pathogenic organisms.
Although primarily parasites of humans, they can also sustain
themselves on birds rabbits, mice and rats.
Feeding is predominantly at night. Hemiptera, meaning
"half-wing", are the true
bugs that include many species that are destructive to agricultural
crops. DNA evidence has shown a close
relationship to the Homoptera, so that
the old classification under one group, Heteroptera, may eventually be
reinstated. They have one-half of their wings
leathery and rough, while the other half is membranous and soft. They are called hemelytra. Sometimes the
leathery wings may be reduced or absent.
There is a rather large scutellum.
Metamorphosis is simple as the nymphs have the same form as adults
except for the lacking wings. The mouthparts arise from the front
of the head and they possess true sucking mouthparts whereas other insects
that suck have modified mouthparts.
Their beak usually has 3-4 segments.
Plant feeding species suck plant juices whereas predatory species suck
blood from their hosts.
The legs are typically the running
type, equipped for rapid movement.
Predaceous species have specialized forelegs for grasping. Some species have legs modified for
rowing. ------------------------------------------ The families of Hemiptera can be divided
into Landforms and Non-land forms depending on whether they are terrestrial,
aquatic or merely inhabit the water surface.
Common species of medical and non-medical importance are discussed for
distinction purposes, and additional information on <Habits>, <Adults> and
<Juveniles> is included when available. Pentatomidae. -- <Habits>; <Adults> & <Juveniles> -- The true
stinkbugs are one of the largest families in the order with a
worldwide distribution. They are
especially predominant in the tropics.
In North America many species are crop pests where they are very
destructive to alfalfa seed. The Say's Plant Bug is a green alfalfa
feeder. All feed on herbaceous plats,
sucking juices. There is one
predaceous subfamily.
These
insects are flattened, shield-shaped insects, 1/4 - 1/2 inch long
usually. Many species have beautiful
colorations, especially in tropical areas.
Antennae are 5-segmented, from which the family derives its name (Penta tomidae) ------------------------------------------ Coreidae. -- Leaf footed bugs include
the squash bug and box elder bug. This is a moderately sized group whose
species have well developed scent glands, which open on the sides of the
thorax. These give off a distinctive
odor when handled. All are plant
feeders and injurious to cucurbits and to some fruit crops. Some are a nuisance as household pests.
Some coreids are brightly colored
that often collect in great numbers on trees and shrubs. The box elder bug in Western North America
can cause a nuisance from the swarms that frequently occur. ------------------------------------------ Lygaeidae. -- <Habits>; <Adults> & <Juveniles> -- The "chinch
bugs" belong to this family, which includes some brilliantly
colored and large species (e.g., milkweed bug). Extremely injurious they prefer to feed on seeds such as
cereals, especially wheat, and have been serious pests in Central North
America. The main symptom of injury
is a wilting and death of grain, especially maize. There are some predaceous species.
Their size ranges from 1/4 to 3/8
inches long. The antennae have four
segments. There are only four of five
veins in the wing. In cold climates
they overwinter in clumps of grasses as adults. Adults migrate to grain fields in springtime and eggs are laid
in the boot of the plants. They will
emigrate to maize as nymphs, which cannot fly but must walk. The False Chinch Bug will feed on most wild plants in Western North
America but will invade herbaceous crops if present. Overwintering is usually in the nymphal
stage. ------------------------------------------ Miridae. -- <Habits>; <Adults> & <Juveniles> -- The plant
bugs, Lygus spp. is a large family with over 5,000 species known. They feed primarily on plant juices and
many are economic pests, and a few are predaceous.
They are fragile insects with drab to
brilliant coloration. The wing has a
unique appearance with two small cells, and the scutellum has a triangle on
its back. Mirids are very active and can run
and fly very rapidly. Several species
have taken up residence with ants.
They injure a wide variety of crops and are especially important on
alfalfa seed production, cotton, clover, celery and various fruits. Both nymphs and adults feed mainly on the
newly developed parts of plants and distort any fruit that might form. In Western North America they rank as one
of the most important economic insects. Overwintering is in the adult
stage. There are approximately four
generations per year, with 20-30 days per generation. ------------------------------------------ Reduviidae. -- <Habits>; <Adults> & <Juveniles> -- These are the assassin bugs and kissing
bugs. Their beak lies back
between their legs in a groove called the stridulatory groove. When the beak is rubbed against the groove
a squeaking sound is produced.
All members of this family are
predaceous and bloodsuckers. The
group has very harmful aspects, as some species are important medically as
vectors of very serious human diseases.
In tropical America Chagas Disease,
caused by trypanosomes is vectored by assassin bugs. Their bite is very painful due to their
toxic saliva. They may even enter
dwellings to feed upon bed bugs and other insects. ------------------------------------------ Nabidae. -- <Habits>; <Adults> & <Juveniles> -- Damsel bugs are small, 3-11.5 mm in length,
slender with their front femora somewhat enlarged. They are all predaceous and feed on many different kinds of
insects. Their color varies from
yellow to brown with well-developed wings.
------------------------------------------ Cimicidae. -- These are the bedbugs,
which possess no wings in any stage of development. They are flattened insects that enable them to squeeze into
fine crevices. They are blood feeders
that favor tight areas, under belts, etc.
Of the more than 45 species known, most feed upon birds, some upon
bats and two species upon humans.
Bedbugs are nocturnal insects that
occur only where their hosts are present.
They require several meals of blood to complete their life cycle, and
when blood is unavailable they can stretch their life cycle. Some people develop a terrific rash while
others are rather insensitive. There
has been no disease associated with Cimicidae, but because of their severe
annoyance a quest for control led to the development of Rotenone as an insecticide. ------------------------------------------ Tingidae. -- These are lace bugs,
whose body's dorsal surface shows a very find network of veins, which gives
it a delicate lace pattern. The
immature stages differ from the adult in possessing many spines.
All species are plant feeders,
preferring to reside on the undersides of leaves. Some form galls on the leaves and many cause some defoliation. For a long time this group was
believed to be ancestral to land, but this has now considered false. Certain predatory forms inhabit a shore or
littoral environment. Many species
are able to spend only a part of their life in water. Some are able to live on the water
surface. Special modifications have enabled
them to exist in aquatic environments.
They have developed special breathing apparatus, some lost the
predatory habit and feed only on plants, and some have had their legs
modified so that they do not sink into the water itself. ------------------------------------------ Belostomatidae. -- <Habits>; <Adults> & <Juveniles> -- Giant
water bugs have a flattened form facilitates movement. Most are brownish and leathery in
appearance and are found in quiet water or in streams. Their front legs are modified for the
predatory habit, and they are very aggressive and active swimmers. Insects, frogs and fish are included in
their diet.
Belostomatids have the habit of
feigning death when captured, and they can inflict painful bites. Their eggs are laid on vegetation or
glued to objects in water, usually in masses containing up to 100 eggs. Oftentimes the female lays eggs on the
back of the male. The glue is water
insoluble. In the water they breathe by means of
a breathing tube. Retractile appendages at the end of the
abdomen lead to spiracles on the 6th abdominal segment. Air reservoirs are also present. They have nocturnal flight habits and
are attracted to light. They can be a
nuisance in tropical areas when they infest buildings. ------------------------------------------ Notonectidae. -- <Habits>; <Adults> & <Juveniles> -- The backswimmers
have a keel-shaped appearance somewhat like a boat. They swim up side down.
They rest on water, their legs extended as oars that have fringes of
hairs, which allow them to propel themselves rapidly. These insects are difficult to capture as
they are very agile and dive rapidly into the water. They inhabit streams and lakes. Some species are brightly colored. They suck the juices of plants and will
travel long distances to water.
------------------------------------------ Gerridae. -- <Habits>; <Adults> & <Juveniles> -- Water
striders have long slender legs.
Body hairs repel water and their claws have been reposition from
apical to pre-apical so that the surface film of the water is not
broken. The hind legs are for
steering, while the front legs are held under the head and shorter then the
rest. They hold their prey with their
front legs, and pierce and suck out the liquid contents.
Tropical members of this insect
group exist in the marine habitat and can be found a few hundred kilometers
out at sea. ------------------------------------------ Mesoveliidae. -- Water Treaders occur on floating
vegetation at the edges of pools or ponds or on logs that project from
water. They can run rapidly over the
water surface. Their size ranges up
to only 5 mm in length. They are
slender insects and usually green or yellow in color. Adults may be either winged or
wingless. They are all predaceous on
small aquatic organisms that occur near the surface of water.
------------------------------------------ Corixidae. -- Water boatmen are
very widespread and probably the most abundant of the Hemiptera. Different species prefer certain kinds of
water. They have a very interesting
wing pattern, which is black and white with a barred effect. Their size is 1/4 to 3/4 inches in length,
and their coloration is protective.
Their legs are modified for rapid movement in water. Ent91 This is the only aquatic group
that is not predaceous, as it feeds on algae with some exceptions. The larvae also feed on minute vegetable
material by scooping it into their mouths.
They have spatulate tarsi.
Some may feed on mosquito larvae.
They are short-lived insects.
Specialized masticating structures are present. Many corixids are very active at
night. SPECIES OF
PRIMARY MEDICAL IMPORTANCE The common bedbugs are members of
this family. They have flattened
bodies that are adapted to hiding in crevices. The wings are degenerated to small pads. The segmented beak is held in a groove on
the ventral surface of the head and thorax.
The head is broad with two large compound eyes. Ocelli are absent and the antennae have 4
segments. A distinctive odor is
associated with bedbugs. Two widespread species are Cimex lectularius L. of temperate latitudes and Cimex hemipterus Fabr. of tropical areas. Other less common species usually not
associated with humans are Leptocimex boueti (Brumpt), Cimex pilosellus Horvath, C. pipistrelli
(Jenyns), Oeciacus spp., Cimexopsis nyctalis List and Haematosiphon inodorus
(Duges). DEVELOPMENT & HABITS Bedbug eggs hatch in 6-7 days at room
temperature. The young nymph begins
to feed after hatching from the egg.
After five molts and about 30 days the adult stage is reached. The number of generations per year depends
on the temperature and host availability.
Dispersal is primarily by human activity. They can hide in clothing
and their eggs are deposited in all their hideouts. EFFECTS ON HUMANS The bites of bedbugs affect people in
different ways depending on their susceptibility. Ranges are from severe irritation to no noticeable effects even
though blood may be lost. Although
experiments have shown that bedbugs can transmit bubonic plague (Pasteurella pestis), it is uncertain
whether they do so naturally. Other
experiments with Leishmania and
Spirochaeta failed. CONTROL Control of minor bedbug infestations
involves cleaning bedding, but in severe cases fumigation of the room or
structure is required. For greater
detail, please refer to Cimicidae. - - - - -
- - - - - - - - - - - - - - - This is a large family of about 410
species that feed on the blood of their hosts. Feeding is largely on other insects or as cannibals. Some species that attack humans are important
vectors of human and other animal diseases.
Their bites may be severe and sometimes take a long time to heal. Several important species that attack
humans are Melanolestes picipes, Rasahus biguttatus and Reduvius personatus. Their appearance is more elongated
than bedbugs, and they are larger and more active. The beak has 3 segments and can cause a painful wound. The elongated head moves freely and eyes
are very conspicuous. Prominent
ocelli may be present and the antennae have 4 segments. There are many subfamilies and genera
in the group, but only a few attack humans, most of which are of minor
importance. Most of the important
species are found in the widespread subfamily Triatominae. In America there are many in this group
that harbor Chagas Disease. Panstrongylus
megistus (Burm.)
of South America is a serious vector of Chagas Disease. The insect is mainly domestic and hides in
any available cover during daytime.
It feeds at night without inflicting a serious wound. The adults are black with red markings on
the prothorax, wings and abdomen.
Eggs are deposited in crevices & holes on the walls of dwellings. Duration of the life cycle is 260-300
days. Triatoma rubrofasciata (DeGeer) occurs
from the Orient to Africa and America, and has a similar life cycle as P. megistus. Triatoma
sanguisuga
(LeConte) is the large conenose of North and Central
America. It is associated with
poultry and adults invade human dwellings.
The adult is 18-20 mm long, flattened and dark brown with pink areas
on the abdomen and the tips of the thickened wings. EFFECTS ON HUMANS Although bites of some Triatominae
may be severe, others give little reaction.
The most important disease associated with this group is Chagas Disease caused by Panstrongylus
megistus. The disease
is spread from Argentina through Central America and Mexico. Symptoms are fever, swelling of eyelids
and face, enlargement of lymphatic glands and destruction of cardiac muscles,
spleen cells and the brain. The body
endothelial tissue cells are also destroyed gradually. Two forms of the disease are acute and
chronic. The acute stage may result
in death in 2-4 weeks. The chronic
state proceeds variably. The insects obtain the trypanosomes
from infected hosts when sucking blood and retain it for two or more
years. The trypanosomes develop in
the insect's intestinal tract and infect humans when the insect defecates in
the wound where it is feeding. In
humans the incubation period is about 12 days and the trypanosomes are found
in the blood during this period.
Later they disappear from the blood and are found in cardiac muscles
and cells of the spleen, liver, brain and most of the tissues, but in a Leishmania form. The trypanosome form may appear
periodically in the blood when the person may serve as a reservoir for the
disease. There have been many species of
animals capable of harboring the trypanosomes, among which are armadillos,
bats, cats and dogs, mice, opossums and wood rats. However, transmission to humans is almost exclusively in
tropical and subtropical regions. CONTROL For Control, please refer to Chagas Disease. Many
other Reduviidae occasionally attack humans causing annoyance. Rhodnius
prolixus Stal of South and Central America readily bites
humans and is also a natural vector of Chagas Disease in Venezuela. Reduvius personatus L. , a widespread
bug, attacks humans and is known as the "Kissing Bug," Rasahus
biguttatus Say and R. thoracicus
Say of the Neotropics are called "Corsairs," Arilus cristatus
L. is the "Wheel Bug" of North America, where it can cause painful
bites. Melanolestes
picipes H.S. & M.
abdominalis H.
S. of North America give severe bites.
In the Baja California Peninsula of Mexico a few cases of a suspected Chagas
Disease illness have occurred, and people are advised not to sleep outdoors
in wilderness areas as the vectors may sequester around rocky boulders.
(Nabidae, Anthocoridae, Pyrochorridae, Lygaeidae Miridae, Notonectidae and Belostomatidae)
Additional
Hemiptera families have species that are known to attack humans, which are
susceptible to their bites. These
insects may have poisonous glands or certain contaminations on their
proboscis may be passed on to the host.
Included here are the Nabidae of tropical regions, the cosmopolitan
Anthocoridae and Pyrochorridae of tropical regions. However, reports of bites by all members of the Hemiptera are
usually vague, so that problem species may be expected in all groups. Following are descriptions of
representatives of the whole order:
Key
References: <medvet.ref.htm> <Hexapoda>
[Additional references may be found at: MELVYL Library] Barrett, T. V.
1991. Advances in triatomine
bug ecology in relation to Chagas disease.
Advances in Disease Vector Research 8: 1843-76. Beard, C. R., C. Cordon-Rosales & R. V.
Durvasula. 2002. Bacterial symbionts and their potential
use in control of Chagas disease
transmission. Ann. Rev. Ent.
47: 123-41. Brenner, R. R. &
A. M. Stoka. 1988.
Chagas Disease Vectors I: Taxonomic, Ecological & Epidemiological
Aspects. CRC Press, Boca Raton, FL. Bryan, R. T., F. Balderrama, R. J. Tonn & J.
C. P. Dias. 1994. Community participation in vector
control: lessons from Chagas disease.
Amer. J. Trop. Medicine & Hyg.
50: 61-71. Carcavallo, R. U., I. G. Galfndez-Giron, J.
Jurberg & H. Lent. 1999. Atlas of Chagas Disease Vectors in the
Americas, Vol. 3, Rio de Janeiro: Oswaldo Cruz
Fundacion. Chinery,
M. 1993. Insects of Britain and Northern
Europe 3rd ed.. Cohen, Allen C. 1990. Feeding Adaptations of Some Predaceous
Hemiptera. Ann. Ent. Soc. Amer. 83 (6): 1215–1223.
Coll,
M.; Ruberson, J.R. (eds.) 1998.
Predatory Heteroptera: their ecology & use in biological
control. CAB Direct Org. Daly,
H. V., John T. Doyen & Alexander H. Purcell 1998. Introduction to Insect Biology and Diversity
2nd ed.. Oxford University Press. pp. 320. Foltz,
J. L. January 23, 2003. "ENY 3005 Families of Hemiptera".
University of Florida.. Forero,
Dimitri. 2008. The Systematics of Hemiptera. Revista
Colombiana de Entomologia. 34(1):
1–21. Goddard, Jerome. 2009.
Bed Bugs (Cimex lectularius) & clinical Consequences
of their bites. JAMA. 301 (13):
1358–1366.
Goddard,
J. & R. deShazo. 2009). "Bed
bugs (Cimex lectularius) and
clinical consequences of their bites".
J. Amer. Med. Assoc. 301(13): 1358–66 Kingman, S.
1991. South America declares
war on Chagas disease. New Scientist
(19 Oct) pp. 16-17. Matheson, R. 1950. Medical Entomology.
Comstock Publ. Co, Inc. 610 p. Olesen, Jacob.
2017. Bed Bug Bites-Pictures,
Treatment & Prevention. http://www.bedbugsbites.net/. Service, M.
2008. Medical Entomology For
Students. Cambridge Univ. Press. 289 p Legner, E. F. 1995. Biological
control of Diptera of medical and veterinary importance. J. Vector Ecology 20(1): 59-120. Legner,
E. F. 2000. Biological control of aquatic
Diptera. p. 847-870. Contributions to a Manual of Palaearctic
Diptera, Vol. 1, Science Herald, Budapest. 978
p. Lent, H. & P. Wygodzinsky. 1979.
Revision of the Triatominae (Hemiptera, Reduviidae), and their
significance as vectors of Chagas disease.
Bull. Amer. Mus. Nat. Hist. 163: 123-520. Matheson, R. 1950. Medical
Entomology. Comstock Publ. Co,
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Reinhardt, Klaus & M. T.
Siva-Jothy. 2007. Biology of the bed bugs (Cimicidae). Ann. Rev. Ent. 52: 351–374.
Ruppert, Edward E., R. Fox,
S. Richard, & R. D. Barnes.
2004. Invertebrate Zool., 7th
edition. Cengage Learning. pp. 728, 748.
Service, M.
2008. Medical Entomology For
Students. Cambridge Univ. Press. 289 p Shcherbakov, D. E. 2000. "Permian faunas of Homoptera Hemiptera in
relation to phytogeography and the Permo-Triassic crisis"
Paleontological Journal
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& J. Nakagawa. 2006.
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Adv. in Parasitology 61:
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