Carnus hemapterus

{{Short description|Species of fly}}

{{Speciesbox

| image = Carnus hemapterus IB.jpg

| image_caption=

| genus = Carnus (fly)

| species = hemapterus

| authority = Nitzsch, 1818 {{cite journal |last1=Nitzsch |first1=C.L. |title=Die Familien und Gattungen der Thierinsekten (Insecta epizoica) als Prodromus einer Naturgeschichte derselben. |journal=Mag. Ent. (Germar) |date=1818 |volume=3 |pages=261–316 |url=https://diptera.myspecies.info/sites/diptera.myspecies.info/files/Nitzsch_1818.pdf |access-date=19 January 2022}}

| synonyms = *Cenchridobia eggeri Schiner, 1862{{cite journal |last1=Schiner |first1=I. R. . |title=Vorlaufiger Commentar zum dipterologischen Theile der "Fauna Austriaca", mit einer naheren Begrundung der in derselben aufgenommenen neuen Dipteren-Gattungen. V. [concl] |journal=Wien. Ent. Monstschr |date=1863 |volume=7 |pages=217–226 |url=https://www.biodiversitylibrary.org/page/31290315#page/57/mode/1up |access-date=17 June 2018}}

• Carnus setosus Stobbe, 1913{{cite journal |last1=Stobbe |first1=R. |title=Zur Kenntnis der Gattung Carnus Nitzsch (= Cenchridobia Schiner) mit 1 nov. sp. (Dipt.) |journal=Deutsche entomologische Zeitschrift |date=1913 |volume=1913 |pages=192–194 |url=https://www.zobodat.at/pdf/Deutsche-Ent-Zeitschrift_1913_0192-0194.pdf |access-date=20 January 2022}}
• Carnus hæmapterus; Newman, 1834{{cite journal |last1=Newman |first1=E. |title=Attempted division of British insects into natural orders |journal=The Entomological Magazine |date=1834 |volume=2 |pages=379–431 |url=https://www.biodiversitylibrary.org/page/8980527#page/405/mode/1up |access-date=10 November 2021}}{{cite web |url= http://diptera.myspecies.info/sites/diptera.myspecies.info/files/Carnidae_catalog_0.pdf|title= World Catalog of the Family Carnidae (Diptera, Schizophora) |last1= Brake|first1=I|year= 2011|publisher= MYIA |access-date=4 January 2013}}

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Carnus hemapterus is a small-bodied and partly black-coloured carnid fly. In their adult stage of life, they are blood-sucking ectoparasites of nestling birds. Within the genus Carnus, this is the only species widespread across Europe and the cold and temperate regions of Asia and North America. Female body length is about 1.5 mm, males are smaller. It typically occurs in the nests of medium- to large-bodied birds, provided that the nest is not on the ground. It is particularly common on the chicks of owls, falcons, rollers, bee-eaters and starlings. Females give birth to larvae that live within the nest and feed on organic debris and the pupae also overwinter there. The emergence of imagines is synchronized to the hatch of host nestlings in the subsequent year. They prefer larger chicks within the nest.{{cite journal |url=http://www.eeza.csic.es/eeza/documentos/Valeraetal.2004.Parasitology.pdf |author1=F. Valera |author2=H. Hoi |author3=A. Darolova |author4=J. Kristofik |year=2004 |title=Size versus health as a cue for host a test of the tasty chick hypothesis |journal=Parasitology |volume=129 |issue=1 |pages=59–68 |doi=10.1017/S0031182004005232 |pmid=15267112 |s2cid=18781148 |url-status=dead |archive-url=https://web.archive.org/web/20070221131312/http://www.eeza.csic.es/eeza/documentos/Valeraetal.2004.Parasitology.pdf |archive-date=2007-02-21 }} Adult flies have a winged and an unwinged variety, the latter being more common. In fact, unwinged flies still carry the basal part of their wings, but the majority of the wing is broken off (see a close view of the above photo). Flies live only on the nestlings before and during the development of the plumage, and disappear later on.{{cite journal |url=http://www.eeza.csic.es/eeza/documentos/Valera%20et%20al.2006.Parasitology.pdf |author1=F. Valera |author2=A. Casas-Criville |author3=M. A. Calero-Torralbo |year=2006 |title=Prolonged diapause in the ectoparasite Carnus hemapterus (Diptera: Cyclorrhapha, Acalyptratae) — how frequent is it in parasites? |journal=Parasitology |volume=133 |pages=179–186 |doi=10.1017/S0031182006009899 |pmid=16623966 |issue=Pt 2 |s2cid=2233395 |url-status=dead |archive-url=https://web.archive.org/web/20070221133030/http://www.eeza.csic.es/eeza/documentos/Valera%20et%20al.2006.Parasitology.pdf |archive-date=2007-02-21 }}{{cite journal|last1= Petrescu|first1= A|last2= Adam|first2= C|year= 2000|title= Carnus hemapterus Nitzsch, 1818 (Diptera: Carnidae) parasite on Merops apiaster L. (Aves: Meropidae) in southern Romania|journal= Travaux du Muséum National d'Histoire Naturelle "Grigore Antipa"|volume= 42|pages= 221–224|url=https://www.researchgate.net/publication/265642452 |access-date= 4 January 2013}}

Infestations by Carnus hemapterus appear to be rather harmless for the host chicks. In spite of that, barn owl females advertise their resistance genes by the dark spots on their breast and belly;{{cite journal |author1=A. Roulin |author2=C. Riols |author3=C. Dijkstra |author4=A.-L. Ducrest |year=2001 |title=Female plumage spottiness signals parasite resistance in the barn owl (Tyto alba) |journal=Behavioral Ecology |volume=12 |pages=103–110 |issue=1 |doi=10.1093/oxfordjournals.beheco.a000371|doi-access=free }} nestlings of heavily spotted females tend to be more resistant. In this study, potential environmental confounding effects were controlled for by cross-fostering chicks.

The faeces and blood remains from these ectoparasitic flies make spots on the eggshell surface of host birds. This contamination appear to increase abundance and diversity of eggshell bacterial loads and, consequently, increase the chance of embryo death.{{cite journal | author1=Lopez-Rull I|author2=Gil M|author3=Gil D|year=2007 |title=Spots in starling Sturnus unicolor eggs are good indicators of ectoparasite load by Carnus hemapterus (Diptera: Carnidae) |journal=Ardeola |volume=54 |pages=131–134}}{{cite journal | author1=Tomás G|display-authors=et al|year=2018 |title=Ectoparasite activity during incubation increases microbial growth on avian eggs|journal=Microbial Ecology |volume=76 |issue=2|pages=555–564|doi=10.1007/s00248-017-1140-6|pmid=29332150|hdl=10481/58162|s2cid=8299771|hdl-access=free}}

Image:Barnowl.jpg|Barn owl, heavily spotted

Image:Schleiereule-IMG 4064.JPG| Barn owl, medium coloration

Image:Tyto alba close up.jpg| Barn owl, weakly spotted