To a geographical distribution of the widest extent, Diptera add a range of habits of the most diversified nature; they are both animal and vegetable feeders, an enormous number of species acting, especially in the larval state, as scavengers in consuming putrescent or decomposing matter of both kinds.
About nine-tenths of Prussian Saxony belongs to the basin of the Elbe, the chief feeders of which within the province are the Saale, with its tributary the Unstrut, and the Mulde, but a small district on the west drains into the Weser.
The Loup system is remarkable for the even dip of its parallel feeders, which once joined the Platte separately, until the latter banked up its deposits across the mouths of their more sluggish currents.
A seasoning of ground fenugreek or spice is sometimes given to shy feeders to encourage them to eat.
In the early spring the existence of a lake could only be certified by pools or hollows of water formed at the mouths of the principal feeders, such as the Khash Rud on the north-east, the Farah Rud on the north-west, and the Helmund, where its old bed terminates at no great distance from the Khash Rud.