THE MOSQUITOES OF THE SOUTHEASTERN STATES 
77 
fourth instar, the ring is incomplete, so far as observed, in the third 
instar. With other species of Aedes the plate is reduced to a small 
dorsal saddle in the third and earlier instars. 
1. Highth abdominal segment with an elongate air tube (figs. 10, B, and 20) ; 
abdomen without palmate hairs____________ ; 
Air tube lacking (spiracles sessile); some abdominal segments with 
dorsal palmate hairs (figs. 10, A, and 22, B)____________ Anopheles 
2. Air tube of normal shape, cylindrical or fusiform_=_——__--=-_ 
| 6 Distal half of air tube attenuated (fig. 23, B), with saw-toothed projec- 
tions at tip adapted for piercing the roots of aquatic plants_ Mansonia 
SerAi TE Cues With as peClens: (dies 24 7Ab) pee kee ee Ee es 
Air tube without a pecten (Megarhinus, Orthopodomyia, Wyeomyia) ___ 
Mouth Lrushes 
a \ 
ial 
ue 
Y ee 
\ 
\\ 
----Lower head hair 
ae aD, 
C—O an | 
0.5 mm. 
FIGURE 21.—Head of larva of Aedes vexans. 
4. Head hairs normal, slender, frequently multiple; head wider than long, 
BOUIN C Chasers Sere 5 ae A Re aes 
Head elongate, elliptical; upper and lower head hairs single, stout, 
spinelike (fig. 25, 4). [Highth abdominal segment with a lateral plate 
having a row of teeth on its posterior margin; air tube with one pair 
of ventral brushes; anal segment ringed by plate. ]_--_--___ Uranotaenia 
5. Air tube with several paired ventral hair tufts or single hairs, a row of 
y hairs beyond pecten, or a pair of tufts at base (Culex, Theobaldia) ____ 
® Air tube with a single pair of ventral hair tufts, more or less centrally 
placed (sometimes very small or obsolete in Psorophora; a second very 
small pair near apex in Deinocerites). [Antennae in most of the species 
of uniform shape, the hair tuft placed near middle.| (Psorophora, 
ACU C Se elCLNOCCTULES)) mattis Ee SF Beets en Se es ee 
6. Anal segment not completely ringed by plate, or, if ringed, tufts form- 
ing ventral brush posterior to plate (fig. 24, A and B); air tube not 
Anal segment completely ringed by sclerotic plate and plate pierced on 
midventral line by tufts of ventral brush (fig. 23, 4); mouth brushes 
formed of stout prehensile hairs (subgenus Psorophora), or air tube 
large and swollen centrally (except in P. discolor), with few pecten 
spines. [Comb of few scales in a single row. ]_---________ Psorophora 
Upper ead hair 
20 
-] 
34 
