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Carabus nemoralis

By Amy Bagby

Ge­o­graphic Range

Bronze cara­bids (Carabus nemoralis) are found through­out the North­ern United States, from the South­ern coast of Alaska to Mon­tana, and from Wis­con­sin to Maine. Ad­di­tion­ally, these bee­tles can be seen from Por­tu­gal to cen­tral Kaza­khstan (Lorenz, 2021). (Lorenz, 2021)

Habi­tat

Bronze cara­bids are found in wood­land and for­est habi­tats, as well as man-made areas such as parks and gar­dens (Muller, 2021). Also, they are some­times found in agri­cul­tural set­tings as a bi­o­log­i­cal con­trol species (Pi­anez­zola et al., 2013). (Lorenz, 2021; Pi­anez­zola, et al., 2013)

  • Range elevation
    0 to 305 m
    0.00 to 1000.66 ft

Phys­i­cal De­scrip­tion

These bee­tles are rel­a­tively large, with an av­er­age size around 24 mm. They are typ­i­cally black with bronze, green, or pur­ple tints (An­der­son et al., 2000). Fe­males of this species often ap­pear more blue in color on the sec­ond bod­ily seg­ment, also known as the tho­rax. Bronze cara­bids have fil­i­form (mean­ing long, thin, and uni­form in shape) an­ten­nae, a shield-like tho­rax, and mandibles used for grab­bing and chew­ing. Also, they have long, thin legs for the fast cap­ture of prey (Lorenz, 2021). (An­der­son, et al., 2000; Bland and Jaques, 2010; Lorenz, 2021)

Lar­vae of bronze cara­bids are long and black, with many body seg­ments and three dis­tinct legs at­tached to the tho­rax. They have large mandibles and are typ­i­cally only a few mil­lime­ters smaller than the adults (Erb­land, 2014). (Erb­land, 2014)

  • Sexual Dimorphism
  • sexes alike
  • sexes colored or patterned differently
  • Range length
    22 to 26 mm
    0.87 to 1.02 in

De­vel­op­ment

Bronze cara­bids un­dergo com­plete meta­mor­pho­sis. In other words, they must go through an egg, lar­val, pupal, and adult stage to com­plete their life cycle. Most ground bee­tles lay their eggs in soil where they will hatch into lar­vae, and bronze cara­bids are no ex­cep­tion. These lar­vae will then feed and ma­ture until they pu­pate into adults, which can take sev­eral years (New­ton, 2012). (New­ton, 2012)

Re­pro­duc­tion

There is ev­i­dence of in­ter­spe­cific com­pe­ti­tion be­tween males for fe­males of sim­i­lar look­ing species (such as Carabus au­ronitens), as they may be mis­taken for bronze cara­bid fe­males. If the fe­male is re­cep­tive to the male they will mate, but both bee­tles will go on to re­pro­duce with oth­ers of the species dur­ing the breed­ing sea­son. It is not de­scribed if par­ents re­main with their young, or what spe­cific pheromones at­tract mates (Weber and He­im­bach, 2001). (Weber and He­im­bach, 2001)

Bronze cara­bids mate in spring, with lar­vae de­vel­op­ing in the sum­mer after the young hatch. How­ever, it has been shown that sur­viv­ing adult fe­males may re­pro­duce dur­ing the fall. Fe­male bronze cara­bids will lay an av­er­age of around 30 eggs dur­ing their en­tire lay­ing pe­riod. To do this, they will cre­ate a cham­ber in the ground with their ab­domens and lay their eggs in­side of it. Oc­ca­sion­ally, ab­nor­mal tem­per­a­ture fluc­tu­a­tions may af­fect the amount of eggs laid per sea­son. Sex­ual ma­tu­rity oc­curs as soon as the adult bee­tles are ac­tive after meta­mor­pho­sis (Weber and He­im­bach, 2001). (New­ton, 2012; Weber and He­im­bach, 2001)

  • Breeding interval
    Bronze carabids usually breed once yearly in spring, but may breed again in the fall.
  • Breeding season
    The spring breeding season usually occurs from March to May, or in the case of fall breedings, sporadically from August onward.
  • Range eggs per season
    22 to 38
  • Range age at sexual or reproductive maturity (female)
    1 to 3 years
  • Range age at sexual or reproductive maturity (male)
    1 to 3 years

Lifes­pan/Longevity

These bee­tles can live as long as three years in the wild, but not all of them will sur­vive until sex­ual ma­tu­rity (oc­cur­ring at 1-3 years) (New­ton, 2021). As with many other bee­tle species, not all eggs will be fer­til­ized or vi­able. Of the ones that are, some may die as eggs or lar­vae to dis­ease, en­vi­ron­men­tal events, pre­da­tion, or de­vel­op­men­tal er­rors. After meta­mor­pho­sis, the lim­it­ing fac­tors be­come food avail­abil­ity, en­vi­ron­men­tal events, and pre­da­tion. In win­ter, bronze cara­bids will un­dergo di­a­pause to sur­vive the harsh el­e­ments that oth­er­wise would be deadly (Weber and He­im­bach, 2001). (New­ton, 2012; Weber and He­im­bach, 2001)

  • Range lifespan
    Status: wild
    0 to 3 years
  • Typical lifespan
    Status: wild
    0 to 3 years

Be­hav­ior

Bronze cara­bids are soli­tary, motile ground bee­tles known for being preda­cious in both the lar­val and adult stages. Their large mandibles allow for this. They are noc­tur­nal and tend to hide dur­ing the day, so their fa­vored spots are un­der­neath de­bris like fallen wood or large rocks. De­spite being night crea­tures, these cara­bids are very shiny and re­flec­tive, which makes them a lucky find for col­lec­tors. They mainly hunt and live on the ground but, like most bee­tles, can climb if need be (Bland and Jacques, 2010). Bronze cara­bids un­dergo di­a­pause, or a time of halted de­vel­op­ment, un­der­ground in the win­ter to avoid the cold. They may do this for a few win­ters until they have com­pleted their life cycle (Hodek, 2011). (Bland and Jaques, 2010; Hodek, 2011)

Home Range

Bronze cara­bids hail from the Palearc­tic eco­zone. Though they are na­tive to Eu­rope, they have been in­tro­duced into North Amer­ica and can be found in most of the North­ern United States and South­ern Canada with the ex­cep­tion of the Great Plains. (Lorenz, 2021)

Com­mu­ni­ca­tion and Per­cep­tion

Though not much re­search has fo­cused on bronze cara­bids specif­i­cally, most in­sects tend to com­mu­ni­cate through var­i­ous medi­ums. Vi­sual cues allow these bee­tles to watch for be­hav­iors from preda­tors, prey, and po­ten­tial mates as well as to as­sess light­ing con­di­tions. Thig­mo­taxis lets them com­mu­ni­cate through touch, with their an­ten­nae (a very strong sen­sory organ). An­ten­nae also help with chem­i­cal cues such as pheromones that may be com­ing from other bronze cara­bids or preda­tor/prey in­sects. Lastly, in­sects in­clud­ing bronze cara­bids pos­sess small spines or hairs around their bod­ies called setae, which help them sense vi­bra­tions from move­ment and sound (NC State, 2015). (NC State, 2015)

Food Habits

Bronze cara­bids are largely known as gen­er­al­ist preda­tors that will eat al­most any­thing that crosses their paths. This in­cludes other small arthro­pods, slugs and snails, worms, and de­cay­ing ma­te­r­ial. They were con­sid­ered largely mol­lus­civ­o­rous, but they eat a much larger va­ri­ety of food than was pre­vi­ously con­sid­ered (Fawki et al., 2003). Since they catch and eat many types of prey, they have large mandibles for grab­bing and chew­ing, as well as long legs for quick pur­suit of a meal (Bland and Jacques, 2010). (Bland and Jaques, 2010; Fawki, et al., 2003)

Earth­worms are a fa­vored food of bronze cara­bids, since they are most com­mon in their diet. These bee­tles are very well known for eat­ing mul­ti­ple pest species of slugs (such as Arion vul­garis), and thus are com­monly used for bi­o­log­i­cal con­trol. Some re­searchers have found, how­ever, that slug meals are of lower nu­tri­tional qual­ity to these bee­tles, which is a break­away from being con­sid­ered mol­lus­ci­vores (Fawki et al., 2003). (Fawki, et al., 2003)

  • Animal Foods
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms

Pre­da­tion

Bronze cara­bids are well cam­ou­flaged for hid­ing, but are still likely eaten by preda­tors that pur­sue grounded in­sects. No spe­cific ac­counts of pre­da­tion on these bee­tles is recorded (Bland and Jacques, 2010). (Bland and Jaques, 2010)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • No specific known predators have been attributed to bronze carabids

Ecosys­tem Roles

Bronze cara­bids are im­por­tant in­sects in that they are gen­er­al­ists. They hunt in­sects that hu­mans may con­sider pests, as well as con­sume dead ma­te­ri­als to break them down (Fawki et al., 2003). They are also preda­tors of many types of slugs that are agri­cul­tural pests. By using these cara­bids as bi­o­log­i­cal con­trols, they are pro­vided with a food source, and they in turn rid our crops of un­wanted slugs (Pi­anez­zola et al., 2013). (Fawki, et al., 2003; Pi­anez­zola, et al., 2013)

Mu­tu­al­ist Species

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

This species ben­e­fits hu­mans in that they are an asset in con­trol­ling pest pop­u­la­tions of slugs in agri­cul­ture. One study found that net pro­duc­tion of salad greens in­creased greatly after green­house and lab­o­ra­tory in­tro­duc­tions of bronze cara­bids (Renkema et al., 2014). An­other found that they are ef­fec­tive even in semi-field en­vi­ron­ments (Pi­anez­zola et al., 2013). Hu­mans also ben­e­fit from de­creased pest species in na­ture due to the preda­cious na­ture of bronze cara­bids. (Pi­anez­zola, et al., 2013; Renkema, et al., 2014)

  • Positive Impacts
  • research and education
  • controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of bronze cara­bids on hu­mans.

  • Negative Impacts
  • household pest

Con­ser­va­tion Sta­tus

These bee­tles are ei­ther not under threat where they are found or not ex­am­ined, and as such there is no con­ser­va­tion sta­tus at­trib­uted to them.

Con­trib­u­tors

Amy Bagby (au­thor), Col­orado State Uni­ver­sity, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

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.

World Map

Palearctic

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

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

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.

biodegradation

helps break down and decompose dead plants and/or animals

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

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).

diapause

a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

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.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

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.

molluscivore

eats mollusks, members of Phylum Mollusca

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

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.

scavenger

an animal that mainly eats dead animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

solitary

lives alone

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.

vibrations

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

visual

uses sight to communicate

Ref­er­ences

An­der­son, R., D. Mc­Fer­ran, A. Cameron. 2000. The Ground Bee­tles of North­ern Ire­land. Belfast: 1st. Ed. Pub. Ul­ster Mu­seum.

Bland, R., H. Jaques. 2010. How to Know the In­sects. Long Grove, IL: Wave­land Press Inc..

Erb­land, M. 2014. "Bug­guide-Carabus nemoralis" (On-line). Bugguide.​net. Ac­cessed July 17, 2021 at https://​bugguide.​net/​node/​view/​957022/​bgimage.

Fawki, S., S. Smerup Bak, S. Toft. 2003. Food pref­er­ences and food value for the cara­bid bee­tles Pteros­tichus mela­narius, P. ver­si­color and Carabus nemoralis. The 11th Eu­ro­pean Cara­bidol­o­gist Meet­ing 2003 At: Aarhus, Den­mark: 99-109. Ac­cessed July 20, 2021 at https://​www.​researchgate.​net/​publication/​261171431_​Food_​preferences_​and_​food_​value_​for_​the_​carabid_​beetles_​Pterostichus_​melanarius_​P_​versicolor_​and_​Carabus_​nemoralis.

Hodek, I. 2011. Adult Di­a­pause in Coleoptera. Psy­che, 2012: 1-10. Ac­cessed July 20, 2021 at https://​www.​researchgate.​net/​publication/​258382803_​Adult_​Diapause_​in_​Coleoptera.

Lorenz, W. 2021. "Carabus nemoralis O.F. Müller, 1764" (On-line). Global Bio­di­ver­sity In­for­ma­tion Fa­cil­ity. Ac­cessed July 14, 2021 at https://​www.​gbif.​org/​species/​8056040.

NC State, 2015. "In­sect Com­mu­ni­ca­tion" (On-line). NC State Agri­cul­ture and Life Sci­ences. Ac­cessed July 20, 2021 at https://​genent.​cals.​ncsu.​edu/​bug-bytes/​communication/​.

New­ton, B. 2012. "Ground Bee­tles" (On-line). Ken­tucky Crit­ter Files-Ken­tucky In­sects. Ac­cessed July 17, 2021 at https://​www.​uky.​edu/​Ag/​CritterFiles/​casefile/​insects/​beetles/​ground/​ground.​htm.

Pi­anez­zola, E., S. Roth, B. Hat­te­land. 2013. Pre­da­tion by cara­bid bee­tles on the in­va­sive slug Arion vul­garis in an agri­cul­tural semi-field ex­per­i­ment. Bul­letin of En­to­mo­log­i­cal Re­search, 103: 225-232. Ac­cessed July 14, 2021 at https://​web-b-ebscohost-com.​ezproxy2.​library.​colostate.​edu/​ehost/​detail/​detail?​vid=3&​sid=ace41b5f-93a1-40f4-8b2c-78e1ae8a82ce%40sessionmgr102&​bdata=JkF1dGhUeXBlPWNvb2tpZSxpcCx1cmwsY3BpZCZjdXN0aWQ9czQ2NDA3OTImc2l0ZT1laG9zdC1saXZl#​AN=85740364&​db=aph.

Renkema, J., G. Cut­ler, A. Ham­mer­meis­ter. 2014. Using ground bee­tles (Coleoptera: Cara­bidae) to con­trol slugs (Gas­tropoda: Pul­monata) in salad greens in the lab­o­ra­tory and green­house. The Cana­dian En­to­mol­o­gist, 146(05): 567-578. Ac­cessed July 20, 2021 at https://​www.​researchgate.​net/​publication/​269366538_​Using_​ground_​beetles_​Coleoptera_​Carabidae_​to_​control_​slugs_​Gastropoda_​Pulmonata_​in_​salad_​greens_​in_​the_​laboratory_​and_​greenhouse.

Weber, F., U. He­im­bach. 2001. Be­hav­ioural, re­pro­duc­tive and de­vel­op­men­tal sea­son­al­ity in Carabus au­ronitens and Carabus nemoralis (Col., Cara­bidae). Mit­teilun­gen aus der Bi­ol­o­gis­chen Bun­de­sanstalt für Land- und Forstwirtschaft Berlin-Dahlem, 382: 1-194. Ac­cessed July 20, 2021 at https://​www.​researchgate.​net/​publication/​261673139_​Behavioural_​reproductive_​and_​developmental_​seasonality_​in_​Carabus_​auronitens_​and_​Carabus_​nemoralis_​Col_​Carabidae.

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Classification

Classification

  • Kingdom Animalia animals
  • Class Insecta insects
  • Order Coleoptera
  • Family Carabidae carabes, ground beetles
  • Genus Carabus
  • Species Carabus nemoralis