32 American Midland Naturalist Monograph No. 3 



The terminology of the Comstock-Needham system of wing venation is not 

 included since it is rarely used by cuhcidologists. 



The membranous areas bounded by the various veins and cross-veins are 

 known as cells and are clothed with very fine hairs or microtricbia. The 

 veins themselves are clothed with scales, generally of two types: Those 

 v^hich lie close to the veins and which are usually rather short and broad 

 are termed squame scales; those which are suberect and usually narrow are 

 known as outstanding or plume scales. The size, shape, and color of wing 

 scales comprise important taxonomic characters. 



The entire posterior margin of the wing, from the tip to the alula, bears 

 a close-set row of long, slender fi'inge scales. Great variation in alternating 

 spots of pigmentation on the wing-fringe is exhibited by many Anophelines; a 

 characteristic fringe pattern helps to distinguish Psorophora signipennis in 

 the United States. 



With few exceptions, the wing venation is uniform in the Culicinae; the 

 few differences that do occur, however, are convenient and reliable characters 

 for separating some groups. Uranotaenia and Megarhinus, for example, have 

 the apical, forked portion of vein 2 much shorter than its petiole. The posi- 

 tion of cross-vein 3-4 in relation to cross-vein 4-5, the length of the subcostal 

 vein and the length of vein 6 comprise most of the remaining variations. 



Halter. — In mosquitoes, as in other flies, the meta thoracic wings are 

 greatly reduced and not used in flight, except perhaps as balancing organs. 

 These rudimentary structures, the halters, arise behind and slightly above 

 the posterior spiracle from the dorsal region of the metapleuron. Each is 

 made up of three portions: The scabellum, or base; the mid-halter, or stem- 

 like portion; and the capitellum, or terminal knob. Coloration of scaling and 

 integument, particularly of the capitellum, may occasionally be conveniently 

 employed in separating allied species. 



ABDOMEN. — The abdomen is elongate, cylindrical, and made up of 10 

 segments, the first 8 of which are distinct. The 9th and 10th segments of 

 both the males and females have undergone great modification for carrying 

 out je.xual functions. These modified terminal segments of the male, together 

 with the eighth, are discussed separately under "Male Terminalia." These 

 segments of the female, although possessing many generic and subgeneric 

 characters, are not included in this work as they have been little studied and 

 infrequently used by workers in this country. 



Each of the distinct abdominal segments is divisible into a large dorsal 

 tergite and a smaller, ventral sternite, connected laterally by a pleural )nem- 

 brane. Successive segments are joined by intersegmental membranes. It is 

 convenient to speak collectively of the tergites as the dorsum of the abdomen 

 and of the sternites as the venter. Both the dorsum and the venter are shingled 

 with scales in the Culicines, but are usually bare or with few scales in the 

 Anophelines. The first tergite often shows differences in number and position 

 of scales in various Culicine genera and subgenera, as well as differences in 

 scale and integument color. Bicolorous patterns of scales, generally in the 



