The Metanopsilae are made up of the Heteropalpae [palpi long in the male, short in the female; sub-families Culicinae (Culex, &c.) and Heptaphlebomyinae (Heptaphlebomyia)] and Micropalpae [palpi short in both sexes; subfamilies Aedinae (Aedes, &c.) and Haemagoginae (Haemagogus, Uranotaenia, &c.)].
The eggs are usually deposited on the water itself, and while in the case of certain species, such as Culex pipiens or the widely distributed C. fatigans, they are agglutinated together in masses known as "boats" or "rafts" containing from 50 to 400 ova, those of others, such as the Anophelinae and many Culicinae (e.g.
The larvae of species belonging to the Culicinae have a prominent breathing tube, or respiratory siphon, on the penultimate (eighth) abdominal segment, and when taking in air hang head downwards (often nearly vertically) from the surface film.
The Anophelinae have narrow bodies, and generally spotted wings, and when at rest keep body and proboscis in a straight line, often at a considerable angle with the supporting surface; in this way they can be distinguished from Culicinae, which have a humped-up thorax with which the proboscis forms an angle, and in the resting position keep the body parallel to the support.
In the case of filariasis due to Filaria bancrofti, which is common throughout the Tropics, the embryos of the parasite are disseminated by various Culicinae and Anophelinae (Culex pipiens in Queensland; C. fatigans in the West Indies; Myzomyia rossii in India; Pyretophorus costalis in a large portion of tropical Africa; &c.).