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Blattella germanicaGerman cockroach

By Kartik Antani and Amanda Burgeson

Ge­o­graphic Range

Ger­man cock­roaches, be­lieved to have orig­i­nated in South­east Asia, are the most widely dis­trib­uted urban pests. They have been in­tro­duced to all parts of the globe in­clud­ing North Amer­ica, Aus­tralia, Africa, and the Oceanic Is­lands. This ubiq­uity makes Ger­man cock­roaches cos­mopoli­tan, with the only de­ter­rent being cold tem­per­a­tures. ("Ger­man Cock­roach - Blat­tella ger­man­ica", 2004; Ja­cobs, 2007)

Habi­tat

Ger­man cock­roaches live in tem­per­ate or trop­i­cal en­vi­ron­ments. They pre­fer warm, humid weather and are solely ter­res­trial. They in­habit a va­ri­ety of habi­tats, from very moist areas, such as rain­forests and scrub forests, to some­what drier areas such as taigas and chap­ar­rals. They are also found in syl­vatic areas, such as forests and caves, as well as in urban, sub­ur­ban, and rural set­tings. Cold is one of the major fac­tors lim­it­ing the habi­tat of Ger­man cock­roaches. On av­er­age, they are found at el­e­va­tions of 1200 m, and, due to cold tem­per­a­tures and dry­ness, they usu­ally do not re­side above 2000 m. (Ja­cobs, 2007; Valles, 2008)

  • Range elevation
    0 to 2000 m
    0.00 to 6561.68 ft
  • Average elevation
    1200 m
    3937.01 ft

Phys­i­cal De­scrip­tion

Ger­man cock­roaches are ec­tother­mic or­gan­isms. Adults mea­sure 12.7 to 15.88 cm in length (av­er­age 13.0 cm) and weigh be­tween 0.1 and 0.12 g (av­er­age 0.105 g). In gen­eral, Ger­man cock­roaches are monomor­phic with a flat­tened, oval shape, spiny legs, and long an­ten­nae. They are sex­u­ally di­mor­phic. Males have a thin and slen­der body, ta­pered pos­te­rior ab­domen, vis­i­ble ter­mi­nal seg­ments of the ab­domen, and do not have tegmina (leath­ery outer wings). Fe­males tend to be larger and have a stouter body, rounded pos­te­rior ab­domen, and tegmina cov­er­ing the en­tire ab­domen. Ger­man cock­roaches demon­strate bi­lat­eral sym­me­try at all stages of life.

Ger­man cock­roaches are light brown in color with two broad, par­al­lel stripes on the dor­sal side of the body run­ning length­wise. Nymphal cock­roaches re­sem­ble adults in shape; how­ever, they are smaller, darker (dark brown to black), have only a sin­gle stripe down the dor­sal side, and have un­de­vel­oped wings. Egg cap­sules are light tan and round. ("Ger­man Cock­roach - Blat­tella ger­man­ica", 2004; Day, Au­gust 1996; Ja­cobs, 2007; Valles, 2008)

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range mass
    0.1 to 0.120 g
    0.00 to 0.00 oz
  • Average mass
    0.105 g
    0.00 oz
  • Range length
    12.7 to 15.88 cm
    5.00 to 6.25 in
  • Average length
    13.0 cm
    5.12 in

De­vel­op­ment

Ger­man cock­roaches have three de­vel­op­men­tal stages: egg, nymph, and adult. Fe­males de­velop 4 to 8 cap­sules con­tain­ing 30 to 48 eggs each in their life­time. Cap­sules hatch about 28 days after they be­gins to form. A few weeks there­after, a new egg cap­sule be­gins to form. The egg stage varies in du­ra­tion from 14 to 35 days. Ger­man cock­roaches have 6 to 7 nymphal stages oc­cur­ring over a pe­riod of 6 to 31 weeks. They ex­press in­com­plete meta­mor­pho­sis: zy­gotes de­velop within eggs and hatch di­rectly into nymphs, which then grow into adult cock­roaches. The com­plete life cycle of the cock­roach is roughly 100 to 200 days for fe­males, dur­ing which 10,000 de­scen­dants of a sin­gle cock­roach can be pro­duced. (Ja­cobs, 2007; Kunkel, 2008; Mc­Can­d­less, 2005)

Re­pro­duc­tion

The mat­ing be­hav­ior of Ger­man cock­roaches is dri­ven by pheromones given off by fe­males, which are de­tected by the an­ten­nae of males. Ger­man cock­roaches breed con­tin­u­ously with many over­lap­ping gen­er­a­tions pre­sent at any one time. As a re­sult of con­tin­u­ous breed­ing and promis­cu­ity, pop­u­la­tion growth has been shown to be ex­po­nen­tial. (Ja­cobs, 2007; Mc­Can­d­less, 2005)

Ger­man cock­roaches are highly ac­tive sex­u­ally and breed con­tin­u­ously. Rate of breed­ing slows only dur­ing colder months. They breed through­out the year, mate in­dis­crim­i­nately and do not have cy­cles. They uti­lize in­ter­nal fer­til­iza­tion, and fe­males can store sperm for grad­ual re­lease. When nymphs de­velop into adults, they be­come sex­u­ally ac­tive al­most im­me­di­ately. Fe­males pro­duce 4 to 6 cap­sules of 30 to 40 eggs each in their life­time. Con­se­quently, 3 to 4 gen­er­a­tions may live to­gether in a colony. Fe­males lay 120 to 240 eggs per ses­sion (av­er­age 150 eggs), how­ever, they are iteroparous and have mul­ti­ple lay­ings. Prog­eny are dioe­cious and hatch into nymphs in 25 to 30 days (av­er­age 28 days). Ger­man cock­roaches reach in­de­pen­dence be­tween 40 and 150 days of age (av­er­age 65). (Kunkel, 2008; Mc­Can­d­less, 2005)

  • Breeding interval
    German cockroaches breed almost continuously.
  • Breeding season
    German cockroaches breed continuously year round, though breeding slows during colder months.
  • Range eggs per season
    120 to 240
  • Average eggs per season
    150
  • Range gestation period
    20 to 30 days
  • Average gestation period
    28 days
  • Range time to independence
    40 to 125 days
  • Average time to independence
    65 days

Fe­males Ger­man cock­roaches carry their eggs on their back for about 6 weeks be­fore they are laid. They hide their eggs in dis­crete spots, such as cracks, holes, and dark places. They do not, how­ever, pro­vide parental care after eggs are laid. (Day, Au­gust 1996; Ja­cobs, 2007)

  • Parental Investment
  • pre-hatching/birth
    • protecting
      • female

Lifes­pan/Longevity

Male Ger­man cock­roaches, on av­er­age, live 100 to 150 days. Fe­males live much longer, with an av­er­age lifes­pan of 190 to 200 days. (Day, Au­gust 1996; Ja­cobs, 2007)

  • Range lifespan
    Status: wild
    180 to 200 days
  • Typical lifespan
    Status: wild
    100 to 200 days
  • Average lifespan
    Status: wild
    140 days

Be­hav­ior

Ger­man cock­roaches usu­ally live in large groups in warm moist areas (such as bath­rooms and kitchens). Both nymphs and adults are very motile and gen­er­ally for­age at night. Al­though mem­bers of the same colony for­age in si­m­il­iar areas, they scarcely di­rectly com­pete for food. Ger­man cock­roaches are ter­res­trial and adapted for run­ning. Al­though they have wings, they can­not fly. (Ja­cobs, 2007; Kunkel, 2008)

Home Range

Ger­man cock­roaches do not have a spe­cific home range. They usu­ally dwell in homes and in garbage. (Ja­cobs, 2007)

Com­mu­ni­ca­tion and Per­cep­tion

Ger­man cock­roaches use their head gan­glia to vi­su­ally per­ceive their en­vi­ron­ment. They can also use their sube­sophageal gan­glia to con­trol tho­racic fibers, which, when scraped against their body, pro­duce minute noises. This func­tions as an alarm sig­nal and al­lows oth­ers to es­cape pre­da­tion. Ger­man cock­roaches also use cer­tain pheromones to sig­nal ac­tiv­i­ties such as feed­ing and evad­ing preda­tors, al­though these pheromones are gen­er­ally used to sig­nal mat­ing. (Kunkel, 2008)

Food Habits

Ger­man cock­roaches often re­side in or around human res­i­dences due to the ac­cu­mu­la­tion of garbage and de­tri­tus. They con­sume a wide va­ri­ety of foods, in­clud­ing dead or­gan­isms. They usu­ally eat human foods, es­pe­cially starches, sweets, seeds, grains, grease, and meat prod­ucts. Ger­man cock­roaches have also been known to eat soap, tooth­paste, and glue. ("Ger­man Cock­roach - Blat­tella ger­man­ica", 2004; Day, Au­gust 1996; Ja­cobs, 2007)

  • Animal Foods
  • carrion
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Pre­da­tion

Ger­man cock­roaches are preyed upon by other house­hold pests such as spi­ders and cen­tipedes as well as do­mes­tic pets such as dogs and cats. Ger­man cock­roaches can re-grow legs when nec­es­sary. They pro­long their molt­ing cycle to en­sure that the new limb grows in dur­ing a molt. They also dis­play apose­matic col­or­ing in the form of two stripes on their back. Ger­man cock­roaches are rel­a­tively small and are able to hide in small crevices, cracks, and nooks. Nymphs can be as small as 0.7938 mm in width and adults as small as 4.7625 mm. Be­cause of their size and noc­tur­nal habits, they gen­er­ally do not need to out­run preda­tors. ("Ger­man Cock­roach - Blat­tella ger­man­ica", 2004; Kunkel, 2008)

  • Known Predators
    • Spiders Araneae
    • Centipedes Chilopoda
    • domestic cats Felis sylvaticus
    • domestic dogs Canis lupus familiarus

Ecosys­tem Roles

Ger­man cock­roaches are prey to larger house­hold pests. Be­cause they con­sume de­tri­tus, they aid in the cy­cling of nu­tri­ents. They are also key hosts to par­a­sitic bac­te­ria, pro­to­zoans, and viruses, in­clud­ing Blat­ti­cola blat­tae, Ham­mer­sh­midtiella disingi, Nephrid­io­phaga blat­tel­lae, Gre­ga­rina blat­tarum, Lophomonas blat­tarum, Lophomonas stri­ata, En­dolimax blat­tae, En­ta­moeba thom­soni, and Nyc­totherus ovalis. Some of these par­a­sites uti­lize hu­mans and other mam­mals as de­fin­i­tive hosts. (Tsai and Cahill, 1970; Valles, 2008)

Com­men­sal/Par­a­sitic Species
  • Blat­ti­cola blat­tae
  • Ham­mer­sh­midtiella disingi
  • Nephrid­io­phaga blat­tel­lae
  • Gre­ga­rina blat­tarum
  • Lophomonas blat­tarum
  • Lophomonas stri­ata
  • En­dolimax blat­tae
  • En­ta­moeba thom­soni
  • Nyc­totherus ovalis

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive eco­nomic ef­fects of Ger­man cock­roaches on hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Se­cre­tions of Ger­man cock­roaches pro­duce a foul odor when large colonies have amassed. These can also make human foods un­palat­able. This can lead to con­sid­er­able eco­nomic loss, es­pe­cially in parts of the world where food is scarce or ex­pen­sive. Ger­man cock­roaches act as hosts to a num­ber of par­a­sites, such as bac­te­ria, pro­to­zoans, and viruses, which lead to human ail­ments. Fouled food and par­a­sites can lead to food poi­son­ing, dysen­tery, and di­ar­rhea in hu­mans. Bod­ies, frag­ments, waste, and se­cre­tions of cock­roaches are al­ler­gens to hu­mans. These can lead to asthma in young chil­dren. Also, Ger­man cock­roaches may bite hu­mans, feed on par­ti­cles on sleep­ing hu­mans, and cause psy­cho­log­i­cal stress. (Day, Au­gust 1996; Ja­cobs, 2007; Valles, 2008)

Con­ser­va­tion Sta­tus

As they are quite abun­dant, Ger­man cock­roaches are not con­sid­ered a species of con­cern in any part of their range.

Con­trib­u­tors

Kar­tik An­tani (au­thor), Rut­gers Uni­ver­sity, Amanda Burge­son (au­thor), Rut­gers Uni­ver­sity, David V. Howe (ed­i­tor), Rut­gers Uni­ver­sity, Gail Mc­Cormick (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Glossary

Australian

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

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Ethiopian

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

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Nearctic

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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Neotropical

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

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Palearctic

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

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acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

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.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chaparral

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.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cosmopolitan

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.

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

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

fertilization

union of egg and spermatozoan

forest

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

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

introduced

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

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

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.

motile

having the capacity to move from one place to another.

native range

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

nocturnal

active during the night

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.

oriental

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

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oviparous

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

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

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

rainforest

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.

scavenger

an animal that mainly eats dead animals

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

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

social

associates with others of its species; forms social groups.

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

suburban

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

tactile

uses touch to communicate

taiga

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.

temperate

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).

terrestrial

Living on the ground.

tropical

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.

savanna

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.

urban

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

vibrations

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

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

Ref­er­ences

2004. "Ger­man Cock­roach - Blat­tella ger­man­ica" (On-line). North Car­olina Mu­seum of Nat­ural Sci­ences. Ac­cessed Oc­to­ber 18, 2008 at http://​naturalsciences.​org/​microsites/​invasives/​roach.​htm.

Day, E. Au­gust 1996. "Ger­man Cock­roach." (On-line). Vir­ginia Co­op­er­a­tive Ex­ten­sion, Vir­ginia Poly­tech­nic In­sti­tute and State Uni­ver­sity. Ac­cessed Oc­to­ber 14, 2008 at http://​www.​sites.​ext.​vt.​edu/​departments/​entomology/​factsheets/​germanco.​html.

Ja­cobs, S. 2007. "Ger­man Cock­roaches" (On-line). En­to­mol­ogy Notes, Penn­syl­va­nia State Uni­ver­sity. Ac­cessed Oc­to­ber 15, 2008 at http://​www.​ento.​psu.​edu/​extension/​factsheets/​german_​cockroach.​htm.

Kunkel, J. 2008. "The Roach FAQ" (On-line). Uni­ver­sity of Mass­a­chu­setts – Joe Kunkel’s Web Page. Ac­cessed No­vem­ber 14, 2008 at http://​www.​bio.​umass.​edu/​biology/​kunkel/​cockroach_​faq.​html.

Mc­Can­d­less, L. 2005. "CU sci­en­tists un­ravel mat­ing clues of the Ger­man cock­roach" (On-line). Cor­nell Chron­i­cle. Ac­cessed No­vem­ber 14, 2008 at http://​www.​news.​cornell.​edu/​Chronicle/​05/​2.​24.​05/​cockroach.​html.

Tsai, Y., K. Cahill. 1970. Par­a­sites of the Ger­man Cock­roach (Blat­tella ger­man­ica L.) in New York City. The Jour­nal of Par­a­sitol­ogy, 56(2): 375-377. Ac­cessed De­cem­ber 05, 2008 at http://​www.​jstor.​org/​pss/​3277678.

Valles, S. 2008. "Ger­man Cock­roach" (On-line). Uni­ver­sity of Florida In­sti­tute of Food and Agri­cul­tural Sci­ences – Fea­tured Crea­tures. Ac­cessed Oc­to­ber 10, 2008 at http://​entomology.​ifas.​ufl.​edu/​creatures/​urban/​roaches/​german.​htm.

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Classification

Classification

  • Kingdom Animalia animals
  • Class Insecta insects
  • Order Blattodea
  • Family Blattellidae
  • Genus Blattella
  • Species Blattella germanica German cockroach