Corethrellidae are a family of biting

midges A midge is any small fly, including species in several families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some midg ...

, small flying insects belonging to the order

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

, females of which feed on the blood of

frog A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...

s. The members of the family are sometimes known as frog-biting midges. The family currently consists of just one

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

, totalling 115 extant and 10 fossil species worldwide. Most

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

species are found in the lower latitudes, usually associated around the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

. They are tiny flies with a wing length of 0.6-2.5 mm. The

wing venation Insect wings are adult outgrowths of the insect exoskeleton that enable insects to flight, fly. They are found on the second and third Thorax (insect anatomy), thoracic segments (the mesothorax and metathorax), and the two pairs are often referre ...

is similar to

Culicidae Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning "gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "litt ...

(R 4 branched, M 2 branched, Cu 2 branched) with branches of Rs and M nearly parallel. R1 is, however, closer to Sc or almost midway between Sc and R2. They were, from 1962 until 1989, placed as a tribe Corethrellini within the Chaoborinae, a subfamily of Culicidae. Adult female ''Corethrella'' are attracted to the mating calls of male

s, their chosen host taxa. As obligate external parasites, the midges feed almost exclusively on the blood of these frogs. Because of this, ''Corethrella'' follow typical distribution patterns of external parasites and are restricted to only areas with abundant populations of their host frogs. Female midges most likely detect their hosts using a specialized organ called a

Johnston's organ Johnston's organ is a collection of sensory cells found in the pedicel (the second segment) of the antennae in the class Insecta. Johnston's organ detects motion in the flagellum (third and typically final antennal segment). It consists of scol ...

, a collection of sensory cells found on the second antenna segment. There is evidence of host specificity and selection of particular biting sites for some species. ''Corethrella'' species have been observed sucking blood from individuals of the tree frog genus ''

Hyla ''Hyla'' is a genus of frogs in the tree frog family Hylidae. As traditionally defined, it was a wastebasket genus with more than 300 species found in Europe, Asia, Africa, and across the Americas. After a major revision of the family most of th ...

''. Specifically, the North American tree frog species '' Hyla avivoca'', '' Hyla cinerea'' and ''

Hyla gratiosa ''Dryophytes gratiosus'', commonly known as the barking tree frog, is a species of tree frog endemic to the south-eastern United States. Geographic range It is found from Delaware to southern Florida and eastern Louisiana, usually in coastal a ...

'' were recorded as confirmed corethrellid hosts in a 1977 study. A few, select species are known

vector Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

s of frog-specific species of the parasitic protozoan ''

Trypanosoma ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Sarcomastigophora. The name is derived from the Greek ''trypano-'' (bore ...

''. Corethrellid parasitism is thus a recorded cause of

trypanosomiasis Trypanosomiasis or trypanosomosis is the name of several diseases in vertebrates caused by parasitic protozoan trypanosomes of the genus ''Trypanosoma''. In humans this includes African trypanosomiasis and Chagas disease. A number of other diseas ...

among host frog populations. The family contains members that date to the lower

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

Period some 110 million years ago. At least one species, '' Corethrella andersoni'', has been found in Burmese

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Ma ...

deposits dating from this time.

References

Bibliography

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External links

Corethrellidae Corethrellidae are a family of biting midges, small flying insects belonging to the order Diptera, females of which feed on the blood of frogs. The members of the family are sometimes known as frog-biting midges. The family currently consists of ...

in Italian {{Taxonbar, from=Q1627654 Nematocera families Culicoidea