Of the genus _Culicoides_ there are many species occurring in various parts of the world. A number are known to bite man and animals and it is probable that all are capable of inflicting injury. In some localities they are called punkies, in others, sand-flies, a name sometimes also applied to the species of _Simulium_ and _Phlebotomus_. Owing to their very small size they are known by some tribes of Indians as No-see-ums. The larvæ are found in ponds, pools, water standing in hollow tree stumps, and the like. Though probably living chiefly in fresh water, we have found a species occurring in salt water. The larvæ are small, slender, legless, worm-like creatures (fig. 77_c_) with small brown head and twelve body segments. The pupæ (fig. 77_e_) are slender, more swollen at the anterior end and terminating in a forked process. They float nearly motionless in a vertical position, the respiratory tubes in contact with the surface film. The adults are all small, rarely exceeding 2¼ mm. in length. The wings are more or less covered with erect setulæ or hairs and in many species variously spotted and marked with iridescent blotches. The antennæ have fourteen segments, the palpi usually five. The wing venation and mouth-parts are shown in figures 77 and 78. Of the twenty or more species of this genus occurring in the United States the following are known to bite: _C. cinctus_, _C. guttipennis_, _C. sanguisuga_, _C. stellifer_, _C. variipennis_, _C. unicolor_. [Illustration: 78. Culicoides guttipennis; mouth parts of adult. After Pratt.] One of the most widely distributed and commonest species in the Eastern States is _C. guttipennis_ (fig. 77a). It is black with brown legs, a whitish ring before the apex of each femur and both ends of each tibia; tarsi yellow, knobs of halteres yellow. Mesonotum opaque, brown, two vittæ in the middle, enlarging into a large spot on the posterior half, also a curved row of three spots in front of each wing, and the narrow lateral margins, light gray pruinose. Wings nearly wholly covered with brown hairs, gray, with markings as shown in the figure. Length one mm. _Johannseniella_ Will. is a wide-spread genus related to the foregoing. Its mouth-parts are well adapted for piercing and it is said to be a persistent blood sucker, particularly in Greenland. This genus is distinguished from _Culicoides_ by its bare wings, the venation (fig. 163, c), and the longer tarsal claws. There are over twenty North American species. [Illustration: 79. Chrysops univittatus, (×4). After Osborn.] In the Southwestern United States, _Tersesthes torrens_ Towns. occurs, a little gnat which annoys horses, and perhaps man also, by its bite. It is related to _Culicoides_ but differs in the number of antennal segments and in its wing venation (fig. 163, e). The fly measures but two mm. in length and is blackish in color. The antennæ of the female have thirteen segments, the palpi but three, of which the second is enlarged and swollen.