Fleas
Fleas
Fleas are about one thousand species of small insects in the order Siphonaptera, including several hundred species in North America . Adult fleas are external parasites (that is, ectoparasites) of mammals or birds , living on skin or in fur or feathers, and feeding on the blood of their hosts. Some fleas are serious parasites of birds or mammals, and may cause important damage to domestic animals, and sometimes great discomfort to humans. Some species of fleas are vectors of serious diseases of humans or other animals. Infestations of fleas often must be dealt with using topical applications of an insecticide.
Biology of fleas
Fleas have a laterally compressed body, a tough, smooth cuticle with many backward-projecting bristles, and relatively long legs. The mouth parts of fleas include stylets that are used to pierce the skin of the host animal , so that a blood meal can be obtained by sucking.
Fleas have a life cycle characterized by four developmental stages: egg, larva, pupa, and adult. The eggs are usually laid close to the body of the host in a place where the host commonly occurs, for example, on the ground, in a bird or mammal nest, or in carpets or soft furniture in homes. Larval fleas have chewing mouth parts and feed on organic debris and the feces of adult fleas, while adults require meals of bird or mammal blood.
Fleas commonly spend a great deal of time off their hosts, for example, in vegetation or on the ground. They can generally survive for a long time without feeding, while waiting for a suitable opportunity to parasitize a host animal. Fleas are wingless, but they walk well and actively travel over the body of their hosts, and between hosts as well.
Fleas are well known for their jumping ability, with their hind legs providing the propulsive mechanism. As a defensive measure, a flea can propel itself many times its body length through the air. The human flea (Pulex irritans), for example, can jump as high as 7.9 in (20 cm) and as far as 15 in (38 cm), compared with a body length of only a few millimeters.
Species of fleas
There are numerous species of fleas, occurring in various parts of the world. Although most species of fleas are specific to particular host animals for breeding, they are less specific in their feeding and may use various species of birds or mammals for this purpose.
The cat flea (Ctenocephalides felis) can be quite abundant during the hotter months of summer, as can the dog flea (C. canis), when their populations may build up in homes with pet animals. These fleas will also avidly feed on humans, biting especially commonly around the feet and ankles.
The human flea (Pulex irritans) is an important pest of worldwide distribution that can be quite common in human habitations, especially in tropical and sub-tropical countries. The oriental rat flea (Xenopsylla cheopis) is an especially important species, because it is the vector by which the deadly bubonic plague can be spread to humans.
Fleas and diseases
Many of the species of fleas that infest domestic mammals and birds will also utilize humans as a host, although people are not the generally preferred host of these blood-sucking parasites.
The most deadly disease that can be spread to humans by fleas is bubonic plague or black death, caused by the bacterium Pasteurella pestis, and spread to people by various species of fleas, but particularly by the plague or oriental rat flea (Xenopsylla cheopis). Bubonic plague is an extremely serious disease, because it can occur in epidemics that afflict large numbers of people, and can result in high mortality rates. During the European Black Death of medieval times, millions of people died of this disease. There have been similarly serious outbreaks in other places where rats , plague fleas, and humans were all abundant. Bubonic plague is mostly a disease of rodents , which serve as a longer-term reservoir for this disease. However, plague can be transmitted to humans when they serve as an alternate host to rodent fleas during times when rodent populations are large. Plague is mostly spread to humans when infested flea feces are inadvertently scratched into the skin, but transmission can also occur more directly while the fleas are feeding, or when a host accidentally ingests an infected flea.
Another disease that can be spread to humans by fleas is known as endemic or murine flea-borne typhus . This disease is caused by a microorganism known as Rickettsia, and is passed to humans by various species of fleas and lice , but especially by the oriental rat flea. Fleas are also the vector of a deadly disease that afflicts rabbits, known as myxomatosis.
Fleas may also serve as alternate hosts of several tapeworms that can infect humans. These include Dipylidium caninum, which is most commonly a parasite of dogs, but can be passed to humans by the dog flea (Ctenocephalides canis). Similarly, the tapeworm Hymenolepis diminuta can be passed to people by the rat flea (Xenopsylla cheopis).
Resources
books
Borror, D.J., C.J. Triplehorn, and N. Johnson. An Introduction to the Study of Insects. New York: Saunders, 1989.
Carde, Ring, and Vincent H. Resh, eds. Encyclopedia of Insects. San Diego, CA: Academic Press, 2003.
Davies, R.G. Outlines of Entomology. New York: Chapman and Hall, 1988.
Bill Freedman
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- Vector
—Any agent, living or otherwise, that carries and transmits parasites and diseases.
Fleas
Fleas
Fleas are about one thousand species of small insects in the order Siphonaptera, including several hundred species in North America. Adult fleas are external parasites (that is, ectoparasites) of mammals or birds, living on skin or in fur or feathers, and feeding on the blood of their hosts. Some fleas are serious parasites of birds or mammals, and may cause important damage to domestic animals, and sometimes great discomfort to humans. Some species of fleas are vectors of serious diseases of humans or other animals. Infestations of fleas often must be dealt with using topical applications of an insecticide.
Biology of fleas
Fleas have a laterally compressed body, a tough, smooth cuticle with many backward-projecting bristles, and relatively long legs. The mouth parts of fleas include stylets that are used to pierce the skin of the host animal, so that a blood meal can be obtained by sucking.
Fleas have a life cycle characterized by four developmental stages: egg, larva, pupa, and adult. The eggs are usually laid close to the body of the host in a place where the host commonly occurs, for example, on the ground, in a bird or mammal nest, or in carpets or soft furniture in homes. Larval fleas have chewing mouth parts and feed on organic debris and the feces of adult fleas, while adults require meals of bird or mammal blood.
Fleas commonly spend a great deal of time off their hosts, for example, in vegetation or on the ground. They can generally survive for a long time without feeding, while waiting for a suitable opportunity to parasitize a host animal. Fleas are wingless, but they walk well and actively travel over the body of their hosts, and between hosts as well.
Fleas are well known for their jumping ability, with their hind legs providing the propulsive mechanism. As a defensive measure, a flea can propel itself many times its body length through the air. The human flea (Pulex irritans ), for example, can jump as high as 7.9 in (20 cm) and as far as 15 in (38 cm), compared with a body length of only a few millimeters.
Species of fleas
There are numerous species of fleas, occurring in various parts of the world. Although most species of fleas are specific to particular host animals for breeding, they are less specific in their feeding and may use various species of birds or mammals for this purpose.
The cat flea (Ctenocephalides felis ) can be quite abundant during the hotter months of summer, as can the dog flea (C. canis ), when their populations may build up in homes with pet animals. These fleas will also avidly feed on humans, biting especially commonly around the feet and ankles.
The human flea (Pulex irritans ) is an important pest of worldwide distribution that can be quite common in human habitations, especially in tropical and subtropical countries. The oriental rat flea (Xenopsylla cheopis ) is an especially important species, because it is the vector by which the deadly bubonic plague can be spread to humans.
Fleas and diseases
Many of the species of fleas that infest domestic mammals and birds will also utilize humans as a host, although people are not the generally preferred host of these blood-sucking parasites.
The most deadly disease that can be spread to humans by fleas is bubonic plague or black death, caused by the bacterium Pasteurella pestis, and spread to people by various species of fleas, but particularly by the plague or oriental rat flea (Xenopsylla cheopis ). Bubonic plague is an extremely serious disease, because it can occur in epidemics that afflict large numbers of people, and can result in high mortality rates. During the European Black Death of medieval times, millions of people died of this disease. There
KEY TERMS
Vector —Any agent, living or otherwise, that carries and transmits parasites and diseases.
have been similarly serious outbreaks in other places where rats, plague fleas, and humans were all abundant. Bubonic plague is mostly a disease of rodents, which serve as a longer-term reservoir for this disease. However, plague can be transmitted to humans when they serve as an alternate host to rodent fleas during times when rodent populations are large. Plague is mostly spread to humans when infested flea feces are inadvertently scratched into the skin, but transmission can also occur more directly while the fleas are feeding, or when a host accidentally ingests an infected flea.
Another disease that can be spread to humans by fleas is known as endemic or murine flea-borne typhus. This disease is caused by a microorganism known as Rickettsia, and is passed to humans by various species of fleas and lice, but especially by the oriental rat flea. Fleas are also the vector of a deadly disease that afflicts rabbits, known as myxomatosis.
Fleas may also serve as alternate hosts of several tapeworms that can infect humans. These include Dipylidium caninum, which is most commonly a parasite of dogs, but can be passed to humans by the dog flea (Ctenocephalides canis ). Similarly, the tapeworm Hymenolepis diminuta can be passed to people by the rat flea (Xenopsylla cheopis ).
Resources
BOOKS
Carde, Ring, and Vincent H. Resh, eds. Encyclopedia of Insects. San Diego, CA: Academic Press, 2003.
Bill Freedman
Siphonaptera
flea
as fit as a flea in very good health. Recorded from the late 19th century, an example of the emphasis given by alliteration (compare as fit as a fiddle).
flea bite an insignificant inconvenience or cost (literally, a small red mark caused by the bite of a flea).
a flea in one's ear a sharp reproof administered to someone.
see also big fleas have little fleas, lie down with dogs, you will get up with fleas, nothing should be done in haste but gripping a flea.
Flea
FLEA
FLEA (Heb. פַּרְעֹשׁ, parosh). The flea symbolizes an insignificant, loathsome creature (i Sam. 24:15; 26:20). Nevertheless, the ancients did not refrain from calling themselves "parosh," and this was the name of a Judahite family that came with Ezra to Ereẓ Israel from Babylonia (Ezra 2:3), as well as of a Moabite prince (Neh. 10:15). The common flea, Pulex irritans, is a parasite living on human beings and other mammals. Another species is the Chenopsylla cheopsis, which attaches itself to rats. The flea is mentioned several times in talmudic literature where it is stated that contrary to several insects regardedas formed through spontaneous generation, its propagation is sexual (Shab. 107b). In modern times the flea has disappeared almost entirely from the inhabited regions of Israel.
bibliography:
F.S. Bodenheimer, Ha-Ḥai be-Arẓot ha-Mikra, 2 (1956), 292ff.; Tristram, Nat Hist, 305.
[Jehuda Feliks]
Siphonaptera
flea
flea / flē/ • n. a small wingless jumping insect (order Siphonaptera) that feeds on the blood of mammals and birds, including the human flea (Pulex irritans) and the cat flea (Ctenocephalides felis). ∎ a water flea (see daphnia).