Pulex irritanshuman flea

Geographic Range

Pulex irritans has been found all over the world except for the Arctic. This species likely originated in Central or South America, but thrives in temperate climates. (Buckland and Sadler, 1989)


As a nidicolous ectoparasite, an adult P. irritans is found on its hosts exterior when it needs to feed. Hosts for this species are generally mammals, and are primarily larger carnivores, including humans. When not feeding, P. irritans can be found in nests of host animals or nearly anywhere within a human house. This species has a cosmopolitan distribution, so its habitat varies extensively depending on geographic location. Eggs, larvae and pupae are usually also found in the immediate habitat of the host, if not on the host. Eggs almost always fall off the host, so pupae are also found in the host’s habitat. (Buckland and Sadler, 1989; Roberts and Janovy, 2009; Theobald, 1892)

Physical Description

All fleas have the same general morphology with some minor exceptions in various species. An adult Pulex irritans is reddish-brown in color, with females being 2.5 to 3.5 mm long and males being 2 to 2.5 mm long. The body is laterally compressed and wingless. The abdomen and thorax (nearly continuous) are much larger than the head. The head itself is very short and house a small pair of antennae which are found in small grooves posterior to the ocelli. The antennae have five segments each. Pulex irritans is telmophagus, thus the mouthparts are specialized for piercing and sucking. Unlike most fleas, this species does not have genal or pronotal ctenidia.

All fleas have three pairs of legs, each one with five segments (not including the five tarsal segments). The coxae are greatly enlarged and are the source of fleas’ impressive jumping due to a protein called resilin. Pretarsal claws are present on P. irritans.

The abdomen is subdivided into ten segments. Setae are found on the tergites (dorsal sclerites). The pygidium is a small, circular depression found on the ninth abdominal tergite that functions as a sense organ. The most posterior portions of the abdomen house reproductive organs and genitalia. Females have a sperm-storing structure called the spermatheca. The male genitalia is known as the aedeagus and is arguably the most complex genitalia in the animal kingdom. Males also have two stylets to hold and position the female during copulation.

Pulex irritans eggs are oval and white in color.

All flea larvae resemble maggots with neither legs nor eyes. They are opaque-white colored, have several setae and are extremely active. The head has some sclerotization and is darker than the rest of the body. The most posterior segment has two small, brown hooks.

Pulex irritans pupae are surrounded by a silken, sticky cocoon which easily picks up debris which aids in camouflage. (Buckland and Sadler, 1989; Chandler, 1922; Roberts and Janovy, 2009; Theobald, 1892)

  • Sexual Dimorphism
  • female larger
  • Range length
    2 to 3.5 mm
    0.08 to 0.14 in


Like all fleas, P. irritans is holometabolous (complete metamorphosis, egg-larva-pupa-adult). Eggs hatch in four to six days. The larvae molt three times and then pupate approximately eleven days post-copulation. The length of the larval stage depends on temperature and humidity and ranges from a single day to several months. (Chandler, 1922; Kellogg, 1908; Kelly, et al., 2009)


Currently there are no known mating rituals, mate selection or mate defenses exhibited by Pulex irritans. Like most fleas, Pulex irritans mate opportunistically and are polygynandrous. When two fleas each other, a male will use his maxillary palps to determine if he has encountered a female. (Smit, 1958; Whiting, et al., 2008)

When a male Pulex irritans comes into contact with a female, the male's maxillary palps touch the female, and the male's antennae become erect. The male will then move behind the female and stand on his head. While the male is grasping the female with his antennae, he lifts his abdomen and extends his aedeagus into the female's spermatheca. Insemination can be as short as a few seconds, but typically takes more time. The female will later haphazardly lay between eight and twelve eggs individually. The eggs hatch about four to six days later. The larvae pupate approximately eleven days post-copulation, and emerge from their cocoons to become adults the following day. (Chandler, 1922; Kellogg, 1908; Mullen and Durden, 2009; Theobald, 1892)

  • Breeding interval
    The breeding interval for Pulex irritans is unknown.
  • Breeding season
    Pulex irritans may breed year round.
  • Range gestation period
    4 to 6 days

After females oviposit, Pulex irritans exhibits little parental investment. A significant contribution to a larva's diet is dropped feces from adults. (Chandler, 1922; Kelly, et al., 2009)

  • Parental Investment
  • no parental involvement


An adult P. irritans can live for a few weeks to over a year. A significant portion of the overall lifespan of a single P. irritans can come from the pupal stage, which can last from one day to many months. The egg and larval stage are much shorter in comparison. Therefore, from egg to adult, one P. irritans could live to over two years. (Chandler, 1922; Kellogg, 1908; Kelly, et al., 2009)

  • Range lifespan
    Status: wild
    >2 (high) years


Pulex irritans has three pairs of legs used primarily for walking or running, but has extensive jumping abilities for escaping or getting onto a host. The enlarged coxae contain a highly elastic protein named resilin which is the primary reason for this ability. To jump, the flea will first lock their coxae back, compressing the resilin bands. The jump begins when the tergo-trochanteral depressor muscle relaxes, releasing the coxae. The resilin rapidly expands and causes the flea to summersault through the air at approximately 200 times gravitational acceleration. Jumping fleas can move more than 30 cm in about 0.02 seconds. The pretarsal claws on the middle or hind legs catch onto the host or substrate. Jumps can be made in rapid succession. Oriental rat fleas have been known to make up to 600 jumps per hour for 72 hours straight.

Pulex irritans are usually found in small colonies or groups. They will move onto the host to feed, but are primarily found around the host's immediate habitat. (Buckland and Sadler, 1989; Chandler, 1922; Mullen and Durden, 2009; Theobald, 1892)

Home Range

Specific home range size for Pulex irritans is currently unknown, however most fleas spend their lives on or around a suitable host.

Communication and Perception

Pulex irritans depends mainly on its ocelli and pygidial sensilla or pygidium to find a host. The ocelli can detect changes in light. The pygidium can detect carbon dioxide, air currents and certain odors. Pulex irritans can also sense vibrations.

When looking for a mate, a male will use his maxillary palps to determine if he has encountered a female. (Barrett and Brophy, 2008; Mullen and Durden, 2009; Whiting, et al., 2008)

Food Habits

Adult P. irritans require blood meals in order to produce offspring. They will feed on most any mammal (including humans), but they most commonly parasitize domestic dogs and domestic pigs. Larvae feed on various organic matter found within their habitat, including feces from the adult fleas as it contains undigested blood. (Buckland and Sadler, 1989; Chandler, 1922; Mullen and Durden, 2009)

  • Animal Foods
  • blood


While not directly preying on fleas, many hosts have grooming mechanisms to remove these parasites.

Mesostigmatid mites, pseudoscorpions and various ants, beetles and other arthropods found in the hosts' habitats eat P. irritans. Specifically, black fungus beetles are known to prey upon this species. Eggs, larvae and pupae are especially vulnerable. ("Integrated Pest Management Manual- Fleas", 2010; Mullen and Durden, 2009)

Ecosystem Roles

Pulex irritans is a parasitic species that uses a wide array of hosts, mostly in Mammalia and some in Aves. Since they feed on blood, excessive bites from this species can lead to anemia in the host.

Pulex irritans also serves as a vector for various pathogens including plague-causing bacteria (Yersinia pestis), bacteria causing murine typhus (Rickettsia typhi), bacteria causing feline spotted-fever (Rickettsia felis), protozoa (Nosema pulicis), parasitic nematodes (Steinernema carpocapsae), and pteromalid wasps (Bairamlia fuscipes).

Yersinia pestis can actually lead to the death of the flea. An adult P. irritans obtains the plague agent after feeding from an infected host. The bacteria multiply rapidly in the gut just anterior to the proventriculus and block further blood meals. When the flea attemps to feed, the blood is simply regurgitated back into the host after encountering the mass of Y. pestis in the flea's gut. The regurgitated blood carry some bacteria back into the host, infecting a new individual. Since it cannot feed, the flea will become stressed and attempt to feed more often than usual, intensifying the spread of plague. (Azad, et al., 1997; Azad, 1990; Brouqui and Raoult, 2006; Mullen and Durden, 2009; Ruiz, 2001)

Species Used as Host
Commensal/Parasitic Species
  • bacteria (Yersinia pestis)
  • bacteria (Rickettsia typhi)
  • bacteria (Rickettsia felis)
  • protozoa (Nosema pulicis)
  • parasitic nematodes (Steinernema carpocapsae)
  • pteromalid wasps (Bairamlia fuscipes)

Economic Importance for Humans: Positive

Pulex irritans is a parasite of humans as well as a vector for disease, thus it provides no benefits. (Azad, et al., 1997; Azad, 1990; Brouqui and Raoult, 2006; Rolain, et al., 2005)

Economic Importance for Humans: Negative

Pulex irritans is a vector for the following human diseases: plague (agent: Yersinia pestsis), murine typhus (agent: Rickettsia typhi) and flea-borne spotted rickettsiosis (agent: Rickettsia felis). Bites from P. irritans are slightly raised, often grouped together and cause itching. They can have a bright red appearance due to blood escaping from the puncture wound. Infestations of P. irritans in human households often require drastic removal efforts that may cost significant amounts of money. (Azad, et al., 1997; Azad, 1990; Brouqui and Raoult, 2006; Ruiz, 2001; Sutton, 1916)

Conservation Status

Pulex irritans is a cosmopolitan species with a wide range of hosts. Currently, this species large population size and global distribution do not put it at risk for endangerment. (Buckland and Sadler, 1989)


Jordan Wyrwa (author), University of Michigan-Ann Arbor, Heidi Liere (editor), University of Michigan-Ann Arbor, John Marino (editor), University of Michigan-Ann Arbor, Barry OConnor (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects.



Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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living in the southern part of the New World. In other words, Central and South America.

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living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal


Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.


uses smells or other chemicals to communicate


having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


union of egg and spermatozoan


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

internal fertilization

fertilization takes place within the female's body


referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.


found in the oriental region of the world. In other words, India and southeast Asia.

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reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


specialized for leaping or bounding locomotion; jumps or hops.


an animal that mainly eats blood

scrub forest

scrub forests develop in areas that experience dry seasons.


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


living in residential areas on the outskirts of large cities or towns.


uses touch to communicate


Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.


living in cities and large towns, landscapes dominated by human structures and activity.


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate

year-round breeding

breeding takes place throughout the year


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