Flat bugs

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Flat bugs
Cimex dissimilis

Cimex dissimilis

Class : Insects (Insecta)
Order : Schnabelkerfe (Hemiptera)
Subordination : Bed bugs (heteroptera)
Partial order : Cimicomorpha
Superfamily : Cimicoidea
Family : Flat bugs
Scientific name
Latreille , 1802

The flat bugs (Cimicidae), also known as bed bugs , are a family of bed bugs . All cimicidae live ectoparasitic on mammals and birds , whose blood they suck . As a rule, the larvae and the adult animals are only present at the host to eat. The best-known representative of this family is the bed bug ( Cimex lectularius , lectus Latin for bed, or in the tropics also Cimex hemipterus ), which also sucks on humans. They are the only ectoparasites in the European bug fauna.

Outer shape

Flat bugs reach body lengths between 4 and 12 millimeters. When viewed from above, its body is ovoid-oval, it is very flattened. The head has small complex eyes with only a few ommatidia that protrude laterally from the head contour. The ocelles are missing. The proboscis is relatively short and when at rest only reaches the base of the front hips , the first segment of the labium is greatly shortened, the others about the same length. The pronotum of the trunk section is outlined in front, the head is drawn into this outline. Its side edge is widened outwards in a semicircle. The fore wings ( hemielytrae ) are shortened and reduced to scale-like structures, the hind wings are completely absent. The sides of the rearmost trunk section (the metapleurs) carry the stink glands characteristic of bedbugs, which can give off a strong-smelling secretion that is used for defense. Segments four, five, and six of the abdomen also have such stink glands on the front edge. The abdomen is very flat but widened, often almost circular when viewed from above, it consists of simple tergites and sternites without detached side plates (pleurs). The spiracles lie in the sternites of the segments two to seven, in the first they are absent. The mating organs of the males are strongly modified and asymmetrical, the left paramere has been transformed into a mating organ.

Way of life

About two thirds of the flat bug species parasitize on bats. These are also considered to be the original hosts. The rest are almost exclusively parasites of birds. A number of species, usually bat-bound, can use humans as surrogate or alternative hosts. Only three species are known to specialize in human-bound populations. The well-known bed bug ( Cimex lectularius ) is also originally a parasite of bats (mainly large mouse-eared bats ); the human populations split off several hundred thousand years ago and now specialize in humans; the populations are genetically and morphologically distinguishable. The other species with populations specialized in humans are Cimex hemipterus and Leptocimex boueti .

Flat bugs need an even, balanced microclimate and regular access to their hosts in order to regularly suckle blood, so they usually only occur in their hosts' camps, nests or roosts. They occur mainly on host species that form social associations such as large nurseries or breeding colonies. So you can easily switch from one host to the next. They only look for their host for a blood meal and leave him immediately afterwards to hide. Rarely, but regularly, do individual animals (mostly females with fertilized eggs) sit on escaping hosts and are carried with them when they fly around; these serve as stages of expansion. The animals are usually active in the sleep or rest phase of their host. In hiding away from the host , they are mutually attracted and held together by an odorous substance, an aggregation pheromone . The disturbance of an animal causes the release of a scented secretion from the scent glands characteristic of bed bugs. In addition to a defense function, the secretion also has an alarm function and causes the other animals to flee more or less quickly.


In addition to humans, the main host groups of European flat bugs are pigeons and swallows , but above all bats . But the blood of other mammals and birds can also serve as food. Cimex hirundinis (known under the synonym Oeciacus hirundinis until 2015 ) lives alongside some bird species, for example as a parasite of the dormouse ( Glis glis ). Each molt of a larva and egg-laying by a female requires a blood meal beforehand. The bugs are actively looking for their hosts, and they can travel several meters. They are attracted by their body heat and the exhaled carbon dioxide , in the case of the bed bug over distances of up to about 1.5 meters. To suckle blood, they pierce the skin with their piercing-sucking mouthparts, which each consist of two tubes. Anesthetizing and anti-coagulant substances are introduced through one tube, and the blood is sucked through the other. A sucking process takes about 10 to 20 minutes (with the bed bug) and is carried out about once a week, although other types of flat bugs sometimes had higher sucking frequencies. Each meal of blood doubles or triples the animal's body mass. The animals can survive for up to a year in the absence of suitable hosts.

In paired mycetomas , both sexes harbor endosymbiotic microorganisms . Among other things, they provide vitamins of the B group, which are missing in blood nutrition. In the female, these endosymbionts migrate into the eggs in the ovary and are thus passed on to the offspring.


traumatic insemination at Cimex lectularius

The mating of the flat bugs occurs in an extraordinary way. No advertising behavior has yet been observed. The female is in a sense attacked by the male. It crawls up to the female from behind on the right and mates immediately. Males also mate with previously inseminated females, but reduce the amount of sperm in the process.

The females of the flat bugs have a special organ on the belly side under the skin that does not open to the outside, which is called the sperm gene. It serves only to take in the sperm during copulation and not as a sexual opening . This pocket-shaped organ, visible from the outside as a small swelling, lies between the 4th and 5th sternite . The males - usually guided by this female organ - insert the sperm into the pocket at this point via a needle-shaped copulation organ (one of the parameters of the Aedeagus ) after piercing the skin . Such a mating process, which is occasionally associated with piercing the female skin at any point in the abdomen , is referred to as " traumatic insemination " and also occurs in a similar form in sickle bugs (Nabidae) and flower bugs (Anthocoridae). The mating process, as an injury, reduces the lifespan of the mated female considerably by around 30 to 50 percent, even direct deaths occur, especially with multiple copulations.

The sperm then pass through the hemolymph of the body cavity, initially into the receptaculum seminis , which are located near the ovaries , and finally fertilize the eggs. They are laid later through a genital opening, which is used solely for laying eggs, and when they are laid they already contain more or less developed embryos . The larvae hatching from the eggs are hemimetabolic and pass through five larval stages separated by moulting.

Human and flat bugs

In the industrialized countries, the frequency of the bed bug ( Cimex lectularius ) has decreased significantly compared to previous centuries. However, the species is by no means extinct here. It occurs again and again selectively. Since the bugs live in hiding during the day, they are hardly noticed by humans. Since around 1980 the frequency of bed bug infestation has increased again worldwide, including in Germany. This is attributed to the procrastination caused by the more frequent air travel, which enables constant new infections.

With the exception of the suspected transmission of hepatitis pathogens, the bed bug is of very little parasitological and medical significance . The bites of the bed bug and other flat bugs are painless at first, but can sometimes lead to uncomfortably itchy wheals and allergic reactions.

Taxonomy and species numbers

The family includes about 110 species in 24 genera and 6 subfamilies (Afrocimicinae, Cacodminae, Cimicinae, Haematosiphoninae, Latrocimicinae and Primicimicinae). It is spread all over the world.

In Europe almost exclusively species of the genus Cimex live . A phylogenomic analysis (analysis of the relationships based on the comparison of homologous DNA sequences) only clearly showed in 2015 that the genus Cimex is paraphyletic compared to the previously differentiated genus Oeciacus (with the species hirudinis , vicarius and montandoni ) ; the previous genus Oeciacus was therefore synonymous with Cimex . It is therefore most closely related to the Cimex pipistrelli (which parasitizes on bats) . In 2012, the genus Cacodmus , with the species Cacodmus vicinus , was also newly detected in southern Europe, so that the number of European genera remains at two.

The following species live in Europe

Within the Cimicomorpha , the flat bugs are relatively closely related to the (predatory) family of the flower bugs (Anthocoridae). Together with the Polyctenidae, which also parasitizes on bats, and some other families (also not found in Europe), they form the superfamily Cimicoidea.


  • Ekkehard Wachmann , A. Melber, J. Deckert: Bugs. Volume 1: Revision of the bugs in Germany, Austria and German-speaking Switzerland. Goecke & Evers, Keltern 2006, pp. 211-216. ISBN 3-931374-49-1 .
  • Ekkehard Wachmann: watch bugs - get to know. Neumann - Neudamm, Melsungen 1989, ISBN 3-7888-0554-4 .

Web links

Commons : Flatbugs  - Collection of images, videos, and audio files
  • Brian J. Ford, Debbi J. Stokes: Bug's Eye View . (PDF; 430 kB) with many pictures (English)
  • Cimicidae. Fauna Europaea, accessed November 21, 2006 .

Individual evidence

  1. a b R.T. Schuh, JA Slater: True Bugs of the World (Hemiptera: Heteroptera). Classification and Natural History. Cornell University Press, Ithaca, New York 1995. Cimicidae on page 199 ff.
  2. Ondřej Balvín, Pavel Munclinger, Lukáš Kratochvíl, Jitka Vilímová (2012): Mitochondrial DNA and morphology show independent evolutionary histories of bedbug Cimex lectularius (Heteroptera: Cimicidae) on bats and humans. Parasitological Research 111 (1): 457-469. doi: 10.1007 / s00436-012-2862-5
  3. Ondřej Balvín, Martin Ševčík, Helena Jahelková, Tomáš Bartonička, Maria Orlova, Jitka Vilímová (2012): Transport of bugs of the genus Cimex (Heteroptera: Cimicidae) by bats in western Palaearctic. Vespertilio 16: 43-54.
  4. a b c d Klaus Reinhardt & Michael T. Siva-Jothy (2007): Biology of the Bed Bugs (Cimicidae). Annual Review of Entomology 52: 351-374.
  5. ^ Alvaro Romero (2009): Biology and management of the Bed Bug Cimex lectularius L. (Heteroptera, Cimicidae). University of Kentucky Doctoral Dissertations. Paper 762. download
  6. Klaus Reinhardt, Richard Naylor, Michael T. Siva-Jothy (2003): Reducing a cost of traumatic insemination: female bedbugs evolve a unique organ. Proceedings of the Royal Society London Series B 270: 2371-2375. doi: 10.1098 / rspb.2003.2515
  7. MT Siva-Jothy: Trauma, disease and collateral damage: conflict in cimicids . In: Philosophical Transactions of The Royal Society Biological Sciences (Phil. Trans. R. Soc. B) 2006, No. 361, pp. 269-275, doi: 10.1098 / rstb.2005.1789 .
  8. EH Morrow, G. Arnqvist: Costly traumatic insemination and a female counter-adaptation in bed bugs. In: Proceedings. Biological sciences / The Royal Society (Proc R Soc B) 2003, No. 270, pp. 2377-2381, PMID 14667354 .
  9. ^ TJ Henry (2009): Biodiversity of Heteroptera. In RG Foottit & PH Adler (editors): Insect Biodiversity: Science and Society, Blackwell Publishing (J.Wiley), Oxford. ISBN 978-1-4443-0822-8 : 223-263, number of species on p. 225.
  10. a b Ondřej Balvín, Steffen Roth, Jitka Vilimova (2015): Molecular evidence places the swallow bug genus Oeciacus Stål within the bat and bed bug genus Cimex Linnaeus (Heteroptera: Cimicidae). Systematic Entomology 40: 652-665. doi: 10.1111 / syen.12127
  11. Juan Quetglas, Ondřej Balvín, Radek K. Lučan, Petr Benda (2012): First records of the bat bug Cacodmus vicinus (Heteroptera: Cimicidae) from Europe and further data on its distribution. Vespertilio 16: 243-248.
  12. Ondřej Balvín, Tomáš Bartonička, Nikolay Simov, Milan Paunovic. Jitka Vilimova (2014): Distribution and host relations of species of the genus Cimex on bats in Europe. Folia Zoologica 63 (4): 281-289.
  13. Randall Schuh, Christiane Weirauch, Ward C. Wheeler (2009): Phylogenetic relationships within the Cimicomorpha (Hemiptera: Heteroptera): a total evidence analysis. Systematic Entomology 34: 15-48.