The larval stage is the most important one to be acquainted with because in this stage one can most readily distinguish the anopheline or possible malaria transmitter from a culicine species. One can more readily and quickly make a survey for anophelines by examining the collections of water for larvae than in any other way. The anopheline larva seems to prefer the surface, on which it lies flat and out of the water. To keep it from turning over on its long axis, it has little rosette-like hair tufts on the dorsal surface of the 5 or 6 middle abdominal segments (palmate hairs). There are feathered lateral hairs projecting from thorax and abdominal segments. The head is very small in comparison with the thorax and can be rotated with lightning-like rapidity. There is no projecting breathing tube or syphon from the next to the last abdominal segment, as is characteristic of _Culex_, _Stegomyia_ or any other culicine genus. In addition, culicine larvae do not float parallel to the surface of the water, but hang suspended at an angle, with only the tip of the syphon pushed upward to the surface. The lateral hairs or bristles are not feathered and the head is much larger than that of the anopheline larvae. It is the fact of the surface position of these anopheline larvae which enables them to worm their way over film layers of water or between blades of grass, in grass or rush studded pools or swamps. In the pupal stage it is rather difficult to differentiate species of mosquitoes from each other, so that, other than to recognize that the bloated shrimp-like body is a mosquito pupa, is unnecessary. [Illustration: FIG. 10.—In the above figure note the culicine egg raft, 45° angle position of syphonate larva, parallel attitude of resting mosquito, nonbulbous palpi of male and short palpi of female as contrasted with the anopheline star or ribbon arrangement of eggs, horizontal attitude of asiphonate larva, bradawl attitude of resting mosquito, spotted wings, bulbous palpi of male and long palpi of female mosquito. (From Jordan after Kolle and Hetsch.) MacNeal.] DIFFERENTIATION OF CULICINAE AND ANOPHELINAE It is impossible even for an entomologist to determine the species of mosquitoes without recourse to elaborate keys and tables. It is a comparatively easy matter, however, to decide as to whether the mosquito is a probable malaria transmitter or not.