{{Taksokvir | boja = pink
| naziv = Buha
| slika = Ctenocephalides-canis.jpg
| slika_širina = 250px
| slika_opis = Pseća buha pod mikroskopom
| regnum = Animalia
| phylum = Arthropoda
| classis = Insecta
| ordo = '''Siphonaptera'''
| razdioba_stepen = Podredovi
| razdioba = Ceratophyllomorpha<br/>
Hystrichopsyllomorpha<br/>
Pulicomorpha<br/>
Pygiopsyllomorpha
}}
'''Buha''' je naziv za male sisara i ptica. 

Najpoznatije vrste buha su:

* Mačija buha (''Ctenocephalides felis''),
* Pseća buha (''Ctenocephalides canis''),
* Ljudska buha ili obična buha (''Pulex irritans'')

== Morfologija ==
mini|lijevo|250px|Morfologija buhe
Buhe su mali (duge 1,5 do 3 dlaku i perje domaćina. Noge su im dugačke, posebno zadnji par koji je prilagođen za skakanje (vertikalno do 18 cm, horizontalno do 33 cm<ref>http://ohioline.osu.edu/hyg-fact/2000/2081.html</ref>), oko 200 puta više od dužine tijela, što čini buhu najboljim skakačem u životinjskom svijetu (u odnosu na dužinu tijela). Tijelo im je čvrsto, polirano i pokriveno brojnim dlačicama okrenutim prema nazad<ref>http://edis.ifas.ufl.edu/IG087</ref> što omogućava lakše i brže kretanje. Tijelo može izdržati veliki pritisak, kao što je preživljavanje češanja. Dok se odrasle buhe hrane samo krvlju, njihove larve se hrane organskom materijom kao što je feces odraslih jedinki<ref>http://bugguide.net/node/view/7040</ref>.

== Životni ciklus ==
mini|desno|300px|Jaja mačije buhe
Buhe se razvijaju kompletnom metamorfozom, prolezeći kroz faze larve, lutke i adulta. Životni ciklus počinje kada ženka izbaci jaja nakon hranjenja. Jaja se legu u grupicama do 20 komada, obično na domaćinu, nakon čega padaju na tlo. To se dešava najčešće na mjestima gdje domaćin se odmara ili spava. Jajima je potrebno oko dva dana da se izlegu.<ref>http://ohioline.osu.edu/hyg-fact/2000/2081.html</ref>

Larve zatim izlaze iz jaja i počinju se hraniti dostupnom organskom materijom kao što su mrtvi insekti, feces i sl. Slijepe su i izbjegavaju kukuljicu i ulaze u stadij lutke. Nakon 1-2 sedmice totalno se razvijaju i spremne su izaći iz kukuljice. U slučaju da domaćina nema u blizini mogu ostati u kukuljici dok ne dobiju signal za izlazak, a to je prisustvo domaćina. Signal mogu biti vibracije, zvuk, toplina i ugljen dioksid.<ref>http://ohioline.osu.edu/hyg-fact/2000/2081.html</ref>. U fazi larve ili ličinke mogu i prezimiti. Nakon izlaska iz kukuljice odrasle buhe imaju jednu sedmicu da nađu hranu, nakon čega mogu preživiti od dva mjeseca pa čak i do godinu dana bez hrane. 

Cijeli životni ciklus može trajati od dvije sedmice, pa čak i do nekoliko mjeseci, u zavisnosti od okolnosti.

== Patogeneza ==
mini|desno|200px|Ujedi buha na tijelu
Buhe napadaju različite vrste toplokrvnih kičmenjaka uključujući pse, mačke, ljude, kokoške, zečeve, vjeverice, anemije.

Buhe mogu biti i prenosnici bolesti kao što je npr. kuga, endemski tifus ili himenolepijaza.

{{Taxobox
| name = Flea
| image = Scanning_Electron_Micrograph_of_a_Flea.jpg
| image_width = 200px
| image_caption = Scanning electron microscope (SEM) depiction of a flea
| domain = Eukaryota
| regnum = Animalia
| phylum = Arthropoda
| classis = Insecta
| subclassis = Pterygota
| infraclassis = Neoptera
| superordo = Endopterygota
| ordo = '''Siphonaptera'''
| ordo_authority = Latreille, 1825
| subdivision_ranks = Infraorders
| subdivision =
Ceratophyllomorpha<br />
Hystrichopsyllomorpha<br />
Pulicomorpha<br />
Pygiopsyllomorpha<br />
| synonyms =
Aphaniptera
}}

'''Flea''' is the order '''Siphonaptera''' (some authorities use the name '''Aphaniptera''' because it is older, but names above family rank need not follow the flies (Diptera), based on similarities of the larvae. In any case, all these groups seem to represent a clade of closely related insect lineages, for which the names Mecopteroidea and Antliophora have been proposed.

Some well known flea species include:
* Cat flea (''Ctenocephalides felis''),
* Dog flea (''Ctenocephalides canis''),
* Human flea (''Pulex irritans''),
* Northern rat flea (''Nosopsyllus fasciatus''),
* Oriental rat flea (''Xenopsylla cheopis'').

==Morphology and behavior==
thumb|Diagram of a Flea|350px|left
Fleas are small (1/16 to 1/8-inch (1.5 to 3.3 mm) long), agile, usually dark coloured (for example, the reddish-brown of the cat flea), wingless insects with tube-like mouthparts adapted to feeding on the blood of their hosts. Their bodies are laterally compressed (that is, flattened side to side), permitting easy movement through the hairs or feathers on the host's body (or in the case of humans, under clothes). Their legs are long, the hind pair well adapted for jumping (vertically up to seven inches (18 cm); horizontally thirteen inches (33 cm)<ref name=Ohio> [http://ohioline.osu.edu/hyg-fact/2000/2081.html Fleas, HYG-2081-97] William F. Lyon, Ohio State University entomology page. Accessed 28 December 2006</ref>) - around 200 times their own body length, making the flea the best jumper out of all animals (in comparison to body size). The flea body is hard, polished, and covered with many hairs and short spines directed backward<ref name=Florida>[http://edis.ifas.ufl.edu/IG087 Fleas] - P.G. Koehler and F. M. Oi. Printed July 1993, revised February 2003. Provided by the University of Florida</ref>, which also assists its movements on the host. Its tough body is able to withstand great pressure, likely an adaptation to survive scratching etc. Even hard squeezing between the fingers is normally insufficient to kill the flea; it may be necessary to capture them with adhesive tape,
crush them between the fingernails, roll them between the fingers,
or put them in a fire safe area and burn them with match or lighter. They can also be drowned.

thumb|right|[[Robert Hooke|Hooke's drawing of a flea in ''Micrographia'']]
Fleas lay tiny white oval shaped eggs. Their larvae are small and pale with bristles covering their worm-like body. They are without eyes, and have mouthparts adapted to chewing. While the adult flea's diet consists solely of blood, their larvae feed on various organic matter including the feces of mature fleas.<ref name=BugGuide>[http://bugguide.net/node/view/7040 Order Siphonaptera - Fleas - BugGuide.Net] Accessed 28 December 2006</ref> In the pupae phase the larvae are enclosed in a silken, debris covered cocoon.

==Life cycle and habitat==
Fleas are holometabolous insects, going through the three life cycle stages of larva, pupa and imago (adult). The flea life cycle begins when the female lays after feeding. Adult fleas must feed on blood before they can become capable of reproduction.<ref name="Florida" /> Eggs are laid in batches of up to 20 or so, usually on the host itself, which easily roll onto the ground. As such, areas where the host rests and sleeps become one of the primary habitats of eggs and developing fleas. The eggs take around two days to two weeks to hatch<ref name="Ohio" />.

right|thumb|[[Micrograph of a flea larva.]]
Flea larvae emerge from the eggs to feed on any available organic material such as dead insects, feces and vegetable matter. They are blind and avoid sunlight, keeping to dark places like sand, cracks and crevices, and bedding. Given an adequate supply of food, larvae should pupate within 1-2 weeks. After going through three larval stages they spin a silken cocoon. After another week or two the adult flea is fully developed and ready to emerge from the cocoon. They may however remain resting during this period until they receive a signal that a host is near - vibrations (including sound), heat and carbon dioxide are all stimuli indicating the probable presence of a host.<ref name="Ohio" /> Fleas are known to overwinter in the larval or pupal stages.

Once the flea reaches adulthood its primary goal is to find blood - adult fleas must feed on blood in order to reproduce[http://edis.ifas.ufl.edu/IG087]. Adult fleas only have around a week to find food once they emerge, though they can survive two months to a year between meals. A flea population is unevenly distributed, with 50 percent eggs, 35 percent larvae, 10 percent pupae and 5 percent adults.<ref name="Ohio" /> Their total life cycle can take as little as two weeks, but may be lengthened to many months if conditions are favourable (that is, unfavourable for the fleas). Female fleas can lay 500 or more eggs over their life, allowing for phenomenal growth rates.

==Evolution and classification==
Fleas are apparently related to scorpionflies<ref name=Grimaldi>Grimaldi, D. and Engel, M.S. (snow flea with its rudimentary wings seems to be close to the common ancestor of the 2000 or so currently known varieties of flea, which split off in many directions around 160 million years ago.<ref name="Grimaldi" /> Their evolution continued to produce adaptations for their specialized parasitic niche, such that they now have no wings and their eyes are covered over. The large number of flea species may be attributed to the wide variety of host species they feed on, which provides so many specific ecological niches to adapt to.

Flea systematics is not entirely fixed. While, compared to many other insect groups, fleas have been studied and classified fairly thoroughly, details still remain to be learned about the evolutionary relationships among the different flea lineages.

Infraorder Pulicomorpha
* Superfamily Pulicoidea
** Family Hectopsyllidae – sticktight and chigoe fleas ("chiggers" of Latin America)
** Family Pulicidae – common fleas
* Superfamily Malacopsylloidea
** Family Malacopsyllidae
** Family Rhopalopsyllidae – hosts: marsupials
* Superfamily Vermipsylloidea
** Family Vermipsyllidae – hosts: carnivores
* Superfamily Coptopsylloidea
** Family Coptopsyllidae
* Superfamily Ancistropsylloidea
** Family Ancistropsyllidae
Infraorder Pygiopsyllomorpha
* Superfamily Pygiopsylloidea
** Family Lycopsyllidae
** Family Pygiopsyllidae
** Family Stivaliidae
Infraorder Hystrichopsyllomorpha
* Superfamily Hystrichopsylloidea
** Family Hystrichopsyllidae – hosts: rats and mice. Includes Ctenopsyllidae, Amphipsyllidae
** Family Chimaeropsyllidae
* Superfamily Macropsylloidea
** Family Macropsyllidae
* Superfamily Stephanocircidoidea
** Family Stephanocircidae - hosts: rodents
Infraorder Ceratophyllomorpha
* Superfamily Ceratophylloidea
** Family Ceratophyllidae - hosts: rodents and birds. Includes Dolichopsyllidae
** Family Leptopsyllidae – hosts: mice and rats
** Family Ischnopsyllidae – hosts: bats
** Family Xiphiopsyllidae
<!-- Hypsophthalmidae is almost certainly a synonym, but of what? -->

==Relationship with host==
thumb|left|Flea bites on the back of a human
thumb|right|Flea bite on the waist of a human with no reaction
Fleas attack a wide variety of warm-blooded vertebrates including dogs, cats, humans, chickens, rabbits, squirrels, rats and mice. Fleas are a nuisance to their hosts, causing an itching sensation which in turn may result in the host attempting to remove the pest by biting, pecking, scratching etc the vicinity of the parasite. Fleas are not simply a source of annoyance, however. Some people and animals suffer allergic reactions to flea saliva resulting in rashes. Flea bites generally result in the formation of a slightly-raised swollen itching spot with a single puncture point at the center. The bites often appear in clusters or lines of two bites, and can remain itchy and inflamed for up to several weeks afterwards. Fleas can also lead to hair loss as a result of frequent scratching and biting by the animal, and can cause anemia in extreme cases.

Besides the problems posed by the creature itself, fleas can also act as a vector for disease. For example, fleas transmitted the bubonic plague between rodents and humans by carrying ''Yersinia pestis'' bacteria. Murine typhus (endemic typhus) fever, and in some cases ''Hymenolepiasis'' (tapeworm) can also be transmitted by fleas.

== Flea treatments ==
===For humans===
thumb|right|Flea "dirt" in the fur of a cat is actually excess blood (from host) consumed by the adult flea, passed as feces.

The itching associated with flea anti-itch creams, usually antihistaminics or hydrocortisone. Calamine lotion has been shown to be ineffective for itching.

===For pets===