''Crataerina pallida'', the swift lousefly, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of biting fly in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of louse flies

Hippoboscidae __NOTOC__ Hippoboscidae, the louse flies or keds, are obligate parasites of mammals and birds. In this family, the winged species can fly at least reasonably well, though others with vestigial or no wings are flightless and highly apomorphic. As ...

. These flies are commonly encountered in the nests of the

common swift The common swift (''Apus apus'') is a medium-sized bird, superficially similar to the barn swallow or house martin but somewhat larger, though not stemming from those passerine species, being in the order Apodiformes. The resemblances between t ...

(''Apus apus'') in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

. The lousefly spends its entire

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring * Life-cycle hypothesis ...

associated with swifts. The adult lousefly produce

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e in the late summer months which then

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

te and lie dormant during the winter months inside the vacated swift nest. These parasites have highly aggregated population distribution and high levels of host prevalence. The adult fly then hatch out in spring when the first swift eggs are laid, by the returning adults, and feed on the blood of the nestlings and the adults, sucking about 25 mg of blood every 5 days. They can be a serious pest of adult and nestling swifts. ''Crataerina pallida'' is vertically transmitted ectoparasite, in that it is passed from

parent A parent is a caregiver of the offspring in their own species. In humans, a parent is the caretaker of a child (where "child" refers to offspring, not necessarily age). A ''biological parent'' is a person whose gamete resulted in a child, a male t ...

host on to

offspring In biology, offspring are the young creation of living organisms, produced either by a single organism or, in the case of sexual reproduction, two organisms. Collective offspring may be known as a brood or progeny in a more general way. This ca ...

. ''C. pallida'' are relatively benign, because their own species fitness will depend on successful reproduction of swifts. Evidence suggests that ''C. pallida'' had little if any effect on nestling growth or

fledging Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...

success rate. Image:ApusApusKlausRoggel06.jpg, Eggs of the

(''Apus apus'') and (below) pupae of ''Crataerina pallida''

References

External links

Parasitic flies Parasites of birds Diptera of Europe Diptera of Asia Hippoboscidae Insects described in 1812 {{Parasite-insect-stub