30 American Midland Naturalist Monograph No. 3 



The postnotum is quite similar in all mosquitoes and therefore is of 

 little taxonomic importance. In Wyeomyia, however, there is a small tuft 

 of setae in the middle of the postnotum which helps distinguish the genus. 



The pleural sclerites are not in themselves of great value in a systematic 

 study of the mosquitoes since they are too nearly alike in shape throughout 

 the subfamily and would be difficult to use. In general, the chaetotaxy and 

 scaling of the mesopleural region are the most important. The presence or 

 absence of setae in the post spiracular area (post spiracular bristles) in con- 

 junction with the presence or absence of spiracular bristles is often a character 

 of generic strength. 



The genus Aedes, for example, has postspiracular bristles but no spiracular 

 bristles, while Psorophora has both. The number and position of setae on 

 the sternopleura may offer clues in some instances, since they may be sparse 

 as in Wyeomyia and Uranotaenia, or abundant as in Aedes and Citlex. 

 Deinocerites cancer is quite readily distinguished from other mosquitoes in 

 the southern states by the presence of bronze scales arranged shingle-like 

 on the sternopleura. 



The pre-alar and pre-alar knob may be densely or sparsely clothed, but are 

 not of particular importance. The meron is always bare, and Dossesses no 

 outstanding features in the mosquitoes of the southern United States. The 

 mesepimeron furnishes two hair groups of value, the upper and lower mese- 

 pimeral bristles. Orthopodomyia may be conveniently separated from Man- 

 soma on this basis, since lower mesepimerals are lacking on the former, but 

 present on the latter. 



Meiathorax (Fig. lOA, B) . — The metathorax is much reduced and is of 

 no taxonomic interest. Dorsally the metanotum forms a narrow, usually indis- 

 tinct, transverse band connecting the postnotum with the 1st abdominal ter- 

 gite. Laterally a very small sclerite, the metameron, lies immediately above the 

 hind coxa. Between the metameron and postnotum, and posterior to the 

 mesepimeron, lies the metapleuron. It is separated by a diagonal suture into 

 the metepisternum, with the posterior spiracle on its anterior margin, and 

 the metepimeron, a narrow band bordering the 1st abdominal segment. 



Legs. — Each of the thoracic segments bears a pair of long, slender legs; 

 the jore-legs arising from the prothorax, the middle legs from the meso- 

 thorax, and the hind legs from the metathorax. Each leg is made up of a 

 coxa, trochanter, femur, tibia, and a 5-segmented tarsus. The coxa is short, 

 stout, conical, and connects with the ventral portion of the thorax. The tro- 

 chanter is a small, hinge-like segment between the coxa and the long femur, 

 which is the largest leg segment. The tibia is slender and about as long as 

 the femur. The tarsus is slender and may be about as long as the femur 

 and tibia combined, particularly on the hind or metathoracic pair of legs; 

 segment 1 is the longest segment of the tarsus, often subequal to the tibia; 

 segments 2, 3, 4, and 5 are progressively shorter in most mosquitoes, although 

 the length of one or more of the segments in relation to the others may 

 occasionally vary enough to provide good taxonomic characters (in Ortbo- 



