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Cat flea (Ctenocephalides felis) under the microscope

Cat flea ( Ctenocephalides felis ) under the microscope

Superclass : Six-footed (Hexapoda)
Class : Insects (Insecta)
Subclass : Flying insects (Pterygota)
Superordinate : New winged wing (Neoptera)
Order : Fleas
Scientific name
Latreille , 1825

Fleas (Siphonaptera) form an order in the class of insects and belong to the group of holometabolic insects . Of the approximately 2400 species of fleas, around 80 have been found in Central Europe. The animals are parasites . They reach a length of 1 to 4 millimeters. The best known species is the human flea (Pulex irritans). The largest species are the North American Hystrichopsylla schefferi Chapin , 1919, which parasitizes on the stump-tailed squirrel and grows to a body length of more than 9 millimeters, and the mole flea ( Hystrichopsylla talpae Curtis , 1826), which parasitizes on the European mole ( Talpa europaea Linnaeus , 1758).


Fleas do not have wings . This explains the second part of the scientific name, which is composed of the ancient Greek σίφων síphōn 'tube, siphon, syringe' and ἄπτερος ápteros 'wingless'. Instead, they have strong hind legs that allow them to move quickly, allowing them to make long jumps of almost a meter. The rapid movement of the jump legs is considered to be one of the fastest movements in the entire animal kingdom. In order to achieve this, the contraction speed of the muscles would not be sufficient. This is why fleas have so-called resilin pads in their legs: Resilin is an elastic protein that can be stretched like a bow before jumping and thus enables the flea to jump very long and high. A flea's leap is undirected.

Fleas are characterized by their laterally flattened body, which makes it easier for them to move between the hairs in the fur . The body length of most species is between 1.5 and 4.5 millimeters. In Germany, the largest species is the mole flea (Hystrichopsylla talpae) ( Curtis , 1826), which parasitizes on the European mole and reaches a length of 6 millimeters. The closely related species Hystrichopsylla schefferi Chapin , 1919 is the largest recent flea with a maximum length of more than 9 millimeters. It parasitizes the North American stubby squirrel . Fleas do not have compound eyes , but rather a pair of single-lensed point eyes . The mouthparts have been converted into a combined proboscis and proboscis (hence the first part of the scientific name of this order: siphon, Greek for "pipe, tube"). When sucking, the flea performs a real headstand.

Fleas have a very hard chitin shell that makes them very difficult to crush. Rubbing is more likely, however, and you can also crack it with your fingernail. On the body and on the legs they have backward-pointing bristles and tooth combs (ctenidia), which - together with the claws on the legs - make it difficult to comb fleas out of the hair.

Way of life

Fleas are parasites that live on warm-blooded animals, with 94 percent of all species parasitizing on mammals and about 6 percent on birds. Fleas do have preferences for certain host animals , but are not exclusively dependent on them. Rather, fleas seem to have a greater bond with their nests (animal nests, but also cushions, see below) than with their hosts.

Flea larva

Thus, humans are also attacked by flea species other than human fleas ( Pulex irritans Linnaeus , 1758). Pet owners should also make sure that their animals are free of fleas for the sake of their own health.

Fleas are attracted by the carbon dioxide in the air, heat and movement of animals. After a large meal, fleas can go without food for up to two months.

In apartments, fleas feel comfortable in carpets and upholstered furniture, which is where they spend most of their time. They only seek out people to suck blood .

A flea can live for a maximum of 1½ years. The lifespan of the adult rat flea is five to six weeks. The larval development takes eight days (warm room temperature) up to a year, depending on the temperature. There are three larval stages and a dormant pupal stage.

According to their behavior, the fleas are divided into two groups: nest fleas and fur fleas. The nest fleas remain stationary near their host's sleeping place in a dark and dry environment. They come out of their hiding place at night, attack the host and then disappear back into hiding, where they lay their eggs. They are extremely light-shy and do not love any change of location. It is therefore very rarely found on clothing that is in use. It is characteristic that the host is infested with bites indiscriminately over the whole body. The best known representative is the human flea, which stays in the dark places of the bed during the day. The fur fleas, however, remain seated on their host and migrate with him. They therefore easily tolerate light, jump on people and get stuck in their clothes. But they only take human blood as an exception when there are no more rats available.

The larvae of the fleas mostly feed on decaying organic matter near their future hosts. The feces of adult fleas can therefore also count as food.


Reproduction requires a certain temperature range. If the temperature falls to 5 ° C and below, reproduction ceases, and below 10 ° C it decreases significantly . However, this does not mean that fleas do not multiply in the temperate and northern latitudes in winter. They reproduce there in apartments and stables all year round.

The males have special clamp organs that they use during copulation . The female lays the relatively large eggs in packets of around 10 and has to eat new food every now and then. Females can lay around 400 eggs during their lifetime. The larvae have neither legs nor eyes and are covered with bristles. Development takes place in the host's nest and takes about two to four weeks. The larvae feed on the excretions of the adult animals. Since this is dried blood, an infestation can be effectively detected using this flea droppings. For this purpose, the components combed out with a flea comb are placed on a white absorbent pad (cellulose, pillow case or similar) and slightly moistened. Due to its blood content, the parasite's excretion wipes out reddish.

Female fleas have a seed pouch into which the male injects his ejaculate with pressure. It remains there until the female finds suitable conditions for laying eggs. Only then does the seminal fluid flow out of the semen bag by capillary action.

Harmful effect on humans

Flea bites
Multiple flea bites in humans, scratched and slightly inflamed

If a representative of this species jumps over to humans, its sting causes a small wound there with a more or less intense and extensive itching, which usually leads to people scratching it unnoticed at night. The result is open spots in the skin that can also become inflamed. It is characteristic that the stings are almost always in rows because the fleas are easily irritated or make test stings.

Bacteria (e.g. streptococci and staphylococci) can be transmitted through flea bites, which may lead to inflammation at the bite site due to scratching and itching.

The human flea ( Pulex irritans ) can in rare cases transmit the plague mechanically through its sting / bite . Especially the rat flea ( Xenopsylla cheopis ), the plague flea, has long been known as a biological carrier of the plague due to its sting / bite (see also infection route ). Dog and cat fleas usually stay on their usual hosts , but when they live together they also tend to pass on to humans.

The pathogens of plague, tularemia and murine or endemic typhus (pathogen: bacterium Rickettsia mooseri , vector : primarily rat and flea-like mouse fleas ( Leptinus testaceus ) Mueller ) can be transmitted by tropical flea species . A direct human-to-human transmission is not possible with these fleas.


Left half of the picture: combed out flea droppings; Right half of the picture: reddish wiping of the moistened flea excrement

There are numerous active substances against adult fleas in animals that are intended either for external (spray, spot-on , powder, collar) or internal use. Externally, insecticides such as Fipronil , Imidacloprid , Metaflumizon , Nitenpyram , Selamectin are used. Active substances such as Fluralaner or Spinosad are suitable for internal use in tablet form . Chitin inhibitors such as Lufenuron are suitable for preventing larval development .

In addition, treatment of the animal's surroundings, especially the resting place and preferred location, should be carried out, as fleas are not permanently on the animal and the effectiveness of the active substances applied to the animal is limited to this part of the flea population. The environment is treated by regular wiping, vacuuming and washing of blankets and carpets, supported by chemical flea control with chlorpyrifos , permethrin , propoxur , fenoxycarb , methoprene or combinations of these active ingredients.

Fleas as an attraction

Flea circuses were still a major attraction in the middle of the 20th century . Usually human fleas ( Pulex irritans ) were used as "artists". Females were preferred because they are larger and more visible to both the audience and the trainer. The Marburg scholar Otto Philipp Zaunschliffer wrote humorous works about fleas. The orientalist Enno Littmann has also dedicated an amusing book to the animal through his small collection of stories and songs about the flea (Vom Morgenländischen Flh. Poetry and truth about the flea among Hebrews, Syrians, Arabs, Abyssinians and Turks, Leipzig 1925).

Systematics of fleas

Flea seeker, Giuseppe Maria Crespi , around 1709

The species of fleas occurring in Germany are assigned to six families in four superfamilies:

Order ( ordo )

  • Superfamily ( Super Familia )
    • Family ( familia )
      • Kind ( species )


Fossil evidence

The oldest fossil evidence is a flea about two centimeters long from the Jura of China. The powerful mouthparts suggest a host with a relatively thick skin. Fossil fleas of the Mesozoic Era are also known from the Lower Cretaceous Australia. In addition, inclusions in amber from various tertiary deposits have been described. While some morphological features of the Mesozoic fleas still differ significantly from those of their more recent relatives, the few (as of 2015: 6 specimens) fleas from the Eocene Baltic amber and the somewhat younger Bitterfeld amber (all belonging to the genus Palaeopsylla ) are the current representatives of their Very similar genus. The small insectivores widespread in the Tertiary, such as shrews or moles, are regarded as their hosts. Another three specimens have been found in the somewhat younger Dominican amber .

Proverbs, sayings, metaphors

The close proximity of people to these little tormentors for a long time led to numerous proverbs, language images and expressions:

  • Put a flea in someone's ear (= suggest a plan to them)
  • The flea annoys the lion more than the lion annoys the flea.
  • A flea born in the morning is already a grandmother by noon. (From France : Defamation spreads furiously. )
  • (To have to watch out for) a sack of fleas ( = to have been given an overcomplicated task)
  • Hearing the fleas cough (a high (also imaginary) ability to foresee)
  • An annoying flea , as annoying as a flea
  • Flea circus (like "monkey circus" - a big mess)
  • Whose compatriot is the flea? He is 'brown' and is silent. (= Brunswick)
  • Flea market (etymologically traced back to medieval markets where fleas changed hosts when trading used clothing)
  • (still very common for fabrics in the 19th century :) flea-colored (= black-brown)

See also

Web links

Commons : Fleas  - Collection of images, videos and audio files
Wiktionary: Flea  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Wilhelm Gemoll : Greek-German school and hand dictionary . G. Freytag Verlag / Hölder-Pichler-Tempsky, Munich / Vienna 1965.
  2. a b Siphonaptera: Fleas
  3. Hubert Schumann : Siphonaptera - fleas . In: Bernhard Klausnitzer (ed.): Excursion fauna of Germany . tape 2 . Invertebrates: insects. 11th, revised and expanded edition. Spectrum Academic Publishing House, Heidelberg 2011, p. 820-825 , doi : 10.1007 / 978-3-8274-2452-5_38 .
  4. George P. Holland: Notes on the Genus Hystrichopsylla Rothschild in the New World, with Descriptions of One New Species and Two New Subspecies (Siphonaptera: Hystrichopsyllidae) . In: The Canadian Entomologist . tape 89 , no. 7 , 1957, pp. 309-324 , doi : 10.4039 / ent89309-7 .
  5. a b Quarks & Co: Quarks & Co - WDR television
  6. a b Stefan von Keler: Entomological dictionary. Akademie Verlag, Berlin 1963.
  7. Parasite Flea
  8. floh-befall.de: Which diseases can be transmitted by fleas?
  9. ^ Christian Epe, Monika Linek: Flea infestation and FAD in dogs and cats. In: The practical veterinarian. No. 88, 2007, Supplement 1, pp. 8-14.
  10. LJ Fourie et al .: Control of immature stages of the flea Ctenocephalides felis (Bouche) in carpets exposed to cats treated with imidacloprid. JS Afr Vet Assoc. 2000 Dec; 71 (4): 219-221. PMID 11212931
  11. May R. Berenbaum: Bloodsuckers, State Founders, Silk Manufacturers - The ambiguous relationship between humans and insects . Translated from English by Jorunn Wissmann (Bugs in the System. Insects and their Impact on Human Affairs) . Elsevier, Munich 2004, ISBN 3-8274-1519-5 .
  12. ^ Brian Switek: Super-sized fleas adapted to feed off dinosaurs. In: Nature. 2012, doi : 10.1038 / nature.2012.10135 .
  13. AH Müller: Textbook of Palaeozoology . Volume II: Invertebrates. Part 3, Jena 1978.
  14. Gröhn: inclusions in Baltic amber. Kiel / Hamburg 2015.
  15. ^ S. Ritzkowski: Curiosities in Baltic amber from the Königsberg amber collections, now in the Göttingen collection. In: Amber - views - opinions. Warsaw 2006.
  16. Jacob et al. Wilhelm Grimm: German Dictionary . Vol. 3. dtv, Munich 1984, ISBN 3-423-05945-1 , Sp. 1814.