Haliday, A.H. 1833. Catalogue of the Diptera occurring about Holywood in Downshire. Entomological Magazine, London 1: 154.


Geranomyia is an extensive genus (324 species) of flies that are commonly encountered near aquatic areas such as rivers, streams, or seepage areas. Its members are grouped based both on a supernumerary crossvein at about midlength of wing cell Sc and the elongate mouthparts of the adult fly. The elongation of the mouth parts comprised of the lengthened rostrum and labial palpus and labella. The resulting "trunk-like" appearance is superficially similar to that of Elephantomyia, Helius, and Toxorhina, however these genera have the labial palpus and labella short and rostrum elongate. The genus Zelandoglochina is very similar to Geranomyia, but lacks the supernumerary vein in Sc and has only the labial palpus and labella lengthened, with the rostrum shorter than the remaining head.

Geranomyia canadensis wing
Figure 1. Wing of Geranomyia canadensis Westwood (scale bar = 1.0 mm) 

Geranomyia canadensis hypopygium
Figure 2. Male hypopygium of Geranomyia canadensis (Westwood) (scale bar = 0.5 mm)


Geranomyia is strongly a equatorial group, finding its greatest richness in the Neotropical Region (160 species) and represented by greater than 40 species in the Oriental, Afrotropical, and Australian/Oceanic Regions. The Nearctic and Palearctic Regions are less diverse, being represented by fewer than 20 species each.

Larval Habitat: 

The immature stages of Geranomyia are closely associated with hygropetric habitas such as cliff faces, rocky stream margins, and splash zones. Larvae can be found living within the algal grown that is found in such habitats where the surface is continually wet.