Cecidomyiidae (sometimes misspelled "Cecidomyidae") is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls.
Cecidomyiidae are very fragile small insects usually only 2–3 mm (0.079–0.118 in) in length; many are less than 1 mm (0.039 in) long. They are characterised by hairy wings, unusual in the order Diptera, and have long antennae. More than 6,000 species and 783 genera are described worldwide, but since 1,100 are from well-studied North America, this is certainly an underestimate, and a recent DNA barcoding study estimated the fauna of Canada alone to be in excess of 16,000 species, hinting at a staggering global count of over 1 million cecidomyiid species that have yet to be described, which would make it the most speciose single family in the entire animal kingdom.
Cecidomyiidae are minute to small (0.5–3.0 mm), rarely larger (up to 8 mm, wing length 15 mm) flies with a delicate appearance. Except for a few genera with reduced wings, the eyes are holoptic. The mouthparts are reduced. Cecidomyiid antennae are notably long, with 12–14 segments, (sometimes fewer and up to 40 in some genera). The antennal segments either consist of a basal thickening and petiole or they are binodal, with a proximal node, an intermediate petiole and a distal node. Basal, medial, and apical whorls of hairs occur on the antennal segments. In some species, whorls of loop-shaped sensory filaments are also found, the basal or medial one sometimes being reduced. Some gall flies have only one (basal) whorl of hairs on the antennal segments, and the sensoria (transparent sensory appendages) differ in size and shape. The filaments are thread-like in the Porricondylinae and in all the Cecidomyiinae and take the form of long loops in the supertribe Cecidomyiidi). Ocelli are present only in the Lestremiinae. The wings are usually clear, rarely patterned. The wing bears microtrichia, often as scales, and some species have macrotrichia. The number of longitudinal veins is reduced. Only veins R1, R4+5, M3+4 and Cu1 are well developed in most species. The medial veins M1 and M2 are developed only in primitive groups, and the costa usually has a break just beyond vein R5. The legs are long and slender, without apical bristles.
The genitalia of males consist of gonocoxites, gonostyles, aedeagus, and tergites 9 and 10. Lower (in the evolutionary sense) gall flies often have sclerotized parameres and a more or less transparent plate (the tegmen) located above theaedeagus-the tegmen. In higher gall flies, the parameres and tegmen are not developed. In these, instead, close to the aedeagus, is a triangular basal outgrowth of the gonocoxites called the gonosterna. Supporting structures called apodema are located near the base of the genitalia in males; these are often equipped with two outgrowths. The ovipositor is short, lamelliform, or long, mobile, and in some species, acicular.
The larva is peripneustic. The head is tiny, cone-shaped, and has two posterolateral extensions. The mouthparts are reduced, with minute styliform mandibles. The relatively prominent antennae are two-segmented. Integumental setae or papillae are important in taxonomy since they are constant in number within groups. The prothorax has sclerotized sternal spatula (most). The anus is terminal in the Lestremiinae and paedogenetic in the Porricondylinae and ventral in other groups. The pupa is exarate (in a few species it is enclosed within the last instar larval integument). The anterior spiracle and anterior angle of antennal bases is prominent (most).
Many are economically significant, especially the Hessian fly, a wheat pest, as the galls cause severe damage. Other important pests of this family are the wheat blossom midge Sitodiplosis mosellana, the asian rice gall midge (Orseolia oryzae) and the African rice gall midge O. oryzivora. Other pests are the coffee flower midge (Dasyneura coffeae), Soybean pod gall midge, (Asphondylia yushimai) pine needle gall midge (Thecodiplosis japonensis), the lentil flower midge (Contarinia lentis), the lucerne flower midge (C. medicaginis), and the alfalfa sprout midge (Dasineura ignorata) on the Leguminosae; the black locust tree gall midge (Obolodiplosis robiniae), the swede midge (Contarinia nasturtii), and the brassica pod midge (Dasineura brassicae) on the Cruciferae; the pear midge (Contarinia pyrivora) and the raspberry cane midge (Resseliella theobaldi) on fruit crops; Horidiplosis ficifolii on ornamental figs, and the rosette gall midge (Rhopalomyia solidaginis) on goldenrod stalks, Porrcondylini spp. on Citrus, Lestremia spp. on sweet potato, yam, ginger, garlic, onions, taro tubers, and potato, Lestodiplosis spp., Acaroletes spp., and Aphidoletes spp. on oranges, Lestodiplosis spp., Acaroletes spp., and Aphidoletes spp. on oranges, and Arthrocnodax spp. on limes.   
A large number of gall midge species are natural enemies of other crop pests. Their larvae are predatory, and some are reported as parasitic. The most common prey are aphids and spider mites, followed by scale insects, then other small prey such as whiteflies and thrips, which eat the eggs of other insects or mites. As the larvae are incapable of moving considerable distances, a substantial population of prey must be present before the adults lay eggs, and the Cecidiomyiidae are most frequently seen during pest outbreaks. One species, Aphidoletes aphidimyza, is an important component of biological control programs for greenhouse crops and is widely sold in the United States. In South Africa, Dasineura rubiformis has been deployed against invasive Australian Acacia species.
Cecidomyiids are also known for the strange phenomenon of paedogenesis in which the larval stage reproduces without maturing first. In some species, the daughter larvae consume the mother, while in others, reproduction occurs later on in the egg or pupa.
Parasitoids hosted by the Cecidomyiidae, thereby limiting the gall midge population include the Braconidae (Opiinae, Euphorinae) and chalcidoid wasps in the families Eurytomidae, Eulophidae, Torymidae, Pteromalidae, Eupelmidae, Trichogrammatidae, and Aphelinidae. All contain species which are actual or potential biolological agents.
Data related to Cecidomyiidae at Wikispecies
Aprionus is a genus of wood midges in the family Cecidomyiidae. There are at least 130 described species in Aprionus.Asphondylia
Asphondylia is a genus of gall midges in the family Cecidomyiidae. There are at least 60 described species in Asphondylia.Bibionomorpha
The Bibionomorpha are an infraorder of the suborder Nematocera. One of its constituent families, the Anisopodidae, is the presumed sister taxon to the entire suborder Brachycera. Several of the remaining families in the infraorder (those shown without common names) are former subfamilies of the Mycetophilidae, which has been recently subdivided. The family Axymyiidae has recently been removed from the Bibionomorpha to its own infraorder Axymyiomorpha.
Most representatives of the Bibionomorpha are saprophages or fungivores as larvae with the Cecidomyiidae being predominantly gall-formers. Some Sciarids are common indoor pests, developing large populations in potting soil that has become moldy from overwatering. The larvae of the Bibionidae sometimes migrate in large, snake-like masses to minimize dehydration while seeking a new feeding site.Caryomyia
Caryomyia is a genus of hickory gall midges in the family Cecidomyiidae. There are at least 30 described species in Caryomyia.Cecidomyia
Cecidomyia is a genus of gall midges in the tribe Cecidomyiini.Cecidomyiini
Cecidomyiini is a tribe of gall midges in the family Cecidomyiidae. There are at least 220 described species in Cecidomyiini.Contarinia
Contarinia is a genus of midges, small flies in the family Cecidomyiidae.Cystiphora
Cystiphora is a genus of gall midges in the family Cecidomyiidae. There are about seven described species in Cystiphora.Dasineura
Dasineura is a genus of midges in the family Cecidomyiidae, some of which cause galls on plants such as Dasineura crataegi on hawthorn (Crataegus monogyna) and Dasineura fraxinea on ash (Fraxinus excelsior).Lasiopteridi
The Lasiopteridi is a supertribe of flies from the family Cecidomyiidae. They are often called gall midges or gall gnats.Mayetiola
Mayetiola are a genus of flies from the family Cecidomyiidae. Most species are pests of cereal cropsMidge
Midge is a term used to refer to many species of small flies. The term "midge" does not define any particular taxonomic group, but includes species in several families of non-mosquito Nematoceran Diptera. They are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some midges, such as many Phlebotominae (sand fly) and Simuliidae (black fly), are vectors of various diseases. Many others play useful roles as prey items for insectivores, such as various frogs and swallows. Others are important as detritivores, participating in various nutrient cycles. The habits of midges vary greatly from species to species, though within any particular family, midges commonly have similar ecological roles.
Examples of families that include species of midges include:
Blephariceridae, net-winged midges
Cecidomyiidae, gall midges
Ceratopogonidae, biting midges (also known as no-see-ums or punkies in North America, and sandflies in Australia)
Chaoboridae, phantom midges
Chironomidae, non-biting midges (also known as muckleheads or muffleheads in the Great Lakes region of North America)
Deuterophlebiidae, mountain midges
Dixidae, meniscus midges
Scatopsidae, dung midges
Theumaleidae, solitary midgesMonardia
Monardia is a genus of wood midges, insects in the family Cecidomyiidae. There are at least 40 described species in Monardia.Neolasioptera
Neolasioptera is a genus of gall midges, insects in the family Cecidomyiidae. There are at least 130 described species in Neolasioptera.Rabdophaga
Rabdophaga is genus of flies in the family of gall midges Cecidomyiidae. There are 105 species distributed through Africa, Asia, Europe and North America. Most species of Rabdophaga gall willows (Salix sp.); one exception is R. giraudiana which galls the stems of poplars (Populus sp.).Rhopalomyia
Rhopalomyia is a genus of gall midges, insects in the family Cecidomyiidae. There are at least 220 described species in Rhopalomyia.Sackenomyia
Sackenomyia is a genus of gall midges, insects in the family Cecidomyiidae. There are about five described species in Sackenomyia.Schizomyia
Schizomyia is a genus of gall midges. It has a cosmopolitan distribution.This genus is in the tribe Schizomyiina of the tribe Asphondyliini of the fsmily Cecidomyiinae.Sciaroidea
Sciaroidea is a superfamily in the infraorder Bibionomorpha. There are about 16 families and more than 15,000 described species in Sciaroidea. Most of its constituent families are various gnats.
Extant Diptera families