(2) The presence of variously formed scales on the body and its appendages: the head is clothed with scales, the thorax with hairs or scales, and the abdomen with either hairs or scales, or both; the legs and veins of the wings are always covered with scales, and the palpi are often (as in some Anophelinae) conspicuously scaly.
These genera make up the sub-family Anophelinae, and together include over ioo species.
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.
Larvae of Anophelinae, on the other hand - which are grey, green or brown in colour, and often extremely difficult to see - have no respiratory siphon and lie almost !
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.
The disseminators of malaria are exclusively Anophelinae, but even among these it is only certain species that are dangerous, since the others appear to be incapable of acting as hosts of the parasites.
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.).