294 F. W. EDWARDS. 



Antennal tuft at least two-haired ; shaft nearly always spinose ; 

 eighth abdominal segment with a patch of scales or teeth which may 

 tend to form a single row when few in number . . . . . . . . 5 



2. Antennae rather long ; dorsal surface of abdomen with numerous 



stellate tufts (Finlaya) . . . . . . . . . . • . . . 3 



Antennae short ; dorsal surface of abdomen without conspicuous 

 stellate tufts {Stegomyia) . . . . . . . . . . . . . . 4 



3. Abdominal tufts composed of long, stout bristles . . . . echinus, Edw. 

 Abdominal tufts composed of shorter and much more slender bristles 



geniculatus, Oliv. 



4. Comb-teeth simple alhopidus, Skuse. 



Comb-teeth with lateral basal denticles argenteus, Poiret. 



5. Shaft of antenna quite bare, tuft 2-3-haired {Stegomyia) . . vittatus, Bigot. 

 Shaft of antenna spinose (very slightly so in niariae), tuft generally multiple 6 



Fig. 6. Heads of larvae : a, Aedes echinus, Edw. ; b, Aedes niariae (Serg.). 



6. Pecten with detached, simple teeth outwardly ; hair-tuft very small and 



well beyond middle of siphon ; no long hairs near middle of front 

 margin of thorax . . . . . . . . . . . . . , . . 7 



Either the pecten has no detached simple teeth outwardly, or the hair- 

 tuft is larger and situated practically at the middle of the siphon ; 

 long hair-tufts present near middle of front margin of thorax 

 {Ochlerotatus) . . . . . . . . . . . . . . . . . . 8 



7. The three post-antennal hairs (Lang) nearly in a straight line {Aedes) 



cinereus, Mg. 

 Middle post-antennal hairs almost directly in front of the inner {Eccidex) 



vexans, Mg. 



8. Siphon with three or four pairs of hairs on dorsal (anterior) surface 



rusticus, Rossi. 

 Siphon without hairs on dorsal surface . . . . . . . . . . 9 



9. Antennae longer than the head . . . . . . diantaeus, H. D. & K. 



Antennae shorter than the head . . . . . . . . . . . . 10 



10. Siphonal index about 1 • 5 .. .. .. .. .. .. ..11 



Siphonal index 2 or more ; antennal spinules well-developed . . . . 12 



