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.
Biogeographic Regions: nearctic (Introduced ); palearctic (Introduced ); oriental (Introduced ); ethiopian (Introduced ); neotropical (Native ); australian (Introduced ); oceanic islands (Introduced )
Other Geographic Terms: cosmopolitan
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.
Range length: 2 to 3.5 mm.
Sexual Dimorphism: female larger
Other Physical Features: ectothermic ; bilateral symmetry
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.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: tundra ; taiga ; desert or dune ; savanna or grassland ; chaparral ; forest ; rainforest ; scrub forest ; mountains
Other Habitat Features: urban ; suburban ; agricultural
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.
Animal Foods: blood
Primary Diet: carnivore (Sanguivore )
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.
Ecosystem Impact: parasite
Species Used as Host:
- mammals (Mammalia)
- birds (Aves)
- bacteria (Yersinia pestis)
- bacteria (Rickettsia typhi)
- bacteria (Rickettsia felis)
- protozoa (Nosema pulicis)
- parasitic nematodes (Steinernema carpocapsae)
- pteromalid wasps (Bairamlia fuscipes)
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.
- black fungus beetles (Alphitobius laevigatus)
- mites (Mesostigmata)
- pseudoscorpions (Pseudoscorpionida)
- ants (Formicidae)
- beetles (Coleoptera)
larva of Pulex irritans feeds on dung/debris fallen hair of Homo sapiens
Life History and Behavior
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.
Perception Channels: visual ; tactile ; vibrations ; chemical
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.
Development - Life Cycle: metamorphosis
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.
Status: wild: >2 (high) years.
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.
Mating System: polygynandrous (promiscuous)
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.
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.
Key Reproductive Features: semelparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
After females oviposit, Pulex irritans exhibits little parental investment. A significant contribution to a larva's diet is dropped feces from adults.
Parental Investment: no parental involvement
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Relevance to Humans and Ecosystems
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.
Negative Impacts: injures humans (bites or stings, carries human disease); causes or carries domestic animal disease ; household pest
Pulex irritans is a parasite of humans as well as a vector for disease, thus it provides no benefits.
The human flea, Pulex irritans, is a cosmopolitan flea species that has, in spite of the common name, a wide host spectrum. It is one of six species in the genus Pulex; the other five are all confined to the Nearctic and Neotropical regions. The species is thought to have originated in South America, where its original host may have been the guinea pig or peccary.
This species bites many species of mammals and birds, including domesticated ones. It has been found on dogs and wild canids, monkeys in captivity, opossums, domestic cats, wild felids in captivity, chickens, black rats and Norwegian rats, wild rodents, pigs, free-tailed bats, and other species. It can also be an intermediate host for the cestode Dipylidium caninum.
Flea bites are typically red and inflamed. Overall symptoms include itchiness and rashes. Fleas can spread rapidly and move between areas to include eyebrows, eyelashes, and pubic regions.
Common treatments include body shaving and medicated shampoos and combing.
- Michael F. Whiting, Alison S. Whiting, Michael W. Hastriter & Katharina Dittmar (2008). "A molecular phylogeny of fleas (Insecta: Siphonaptera): origins and host associations". Cladistics 24 (5): 1–31. doi:10.1111/j.1096-0031.2008.00211.x.
- Paul C. Buckland & Jon P. Sadler (1989). "A biogeography of the human flea, Pulex irritans L. (Siphonaptera: Pulicidae)". Journal of Biogeography 16 (2): 115–120. doi:10.2307/2845085. JSTOR 2845085.
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