APPENDIX 231 



3. Hair tufts on thorax and abdomen simple, sparse or absent (4). 

 Thorax and abdomen with star-shaped or stellate hair tufts, Urano- 



taenia sapphirina. 



4. Abdomen with four tracheal gills at tip (5). 



Abdomen with two tracheal gills only; a small whitish species, with 

 head rounded and thorax subquadrate, Wyeomyia smithii. 



5. Antennae arise from sides of anterior part of head (6). 



Antennae arise from near middle of sides of head; the mouth brushes 

 form a club at sides of mouth; a very large species, Psorophora 

 ciliata. 



6. The scales of the eighth abdominal segment are separate (8). 



The scales of the eighth abdominal segment, 5 to 8 in number, are 



arranged on a band (7). 

 The scales are replaced by a series of chitinous bars, arranged in a 



single row (22). 



7. The anal siphon is very large and stout, dilated centrally; antennae 



much longer than head, slender with an even outcurve or con- 

 vexity, Psorophora (J anthinasoma) sayi. 

 The anal siphon shorter, stout, dilated nearer the base; antennae 

 nearly straight slender and shorter than head, Psorophora (Janthi- 

 nasoma) cohmibiae. 



8. The scales are not more than 16 in number and form a small patch (9). 

 The scales number 20 or more and form a large patch (12). 



9. Anna! siphon of moderate length, three times as long as wide, or 



longer (10). 

 Anal siphon short, less than three times as long as wide (11). 



10. About 12 elongate scales in a single row; 12-16 siphonal spines, each 



with one moderate-sized tooth, and sometimes a few very small 



ones below it, Aedes fuscus. 

 Scales 10-15, in partly double row, tapering apically; siphonal spines, 



14-18, simple or with 2 or 3 teeth, Aedes vexans. 

 Scales 7-12 in patch; a small, translucent species, feeding at bottom; 



tracheal gills very long and slender, Aedes dupreei. 

 Scales 6-7, arranged in a curve; tracheal gills, long, slender, uniformly 



tapering, Aedes abserratus. 



11. A stout, black species; the thorax white-banded; antennal tuft com- 



posed of many hairs; tracheal gills very long, Aedes atlanticus. 

 An elongate, slender, gray species; antennal tuft a single bristle; 



tracheal gills short, Aedes triseriatus. 

 A large robust, light species; anal siphon bottle-shaped, outer half 



linear; anal gills slightly longer than width of ninth segment, 



Mansonia perturbans. 



12. Anal siphon short, not much more than twice as long as broad (13). 

 Anal siphon moderate, from 2 l A to 3f£ times as long as broad (15). 

 Anal siphon long, not less than 4 times as long as broad (21). 



13. Stout, compact larva; antennal tuft of several hairs (14). 



Long, slender larva; antennal tuft of 1 or 2 hairs; 25-35 scales in 

 patch; 17-21 siphonal spines, with 2 or 3 long teeth at base, Aedes 

 atropalpus. 



16 



