March, 1905 ] DYAR : NORTH AMERICAN MOSQUITO LARV/E. 25 



33. Brush of tube beyond the pecten 34. 



Brush of tube within the pecten Culex bimaculatus. 



34. Air tube over 2 X J > i ts pecten of 19-22 teeth 35. 



Air tube 2 X * or less, its pecten of 12 to 14 teeth 36. 



35. Scales of the comb with central apical spine shorter than the body of the scale ; 



pecten of air tube of equal teeth ...Grabhamia sollicitans* 



Scales of the comb with central spine about as long as the body of the scale ; 

 pecten of air tube longer outwardly Culex trivittatus. 



36. Spines of comb digitately spined without central one Culex tceniorhynchus. 



Spines of comb feathered on sides with stout central thorn Culex confirmatus. 



37. Anal processes moderate, not conspicuously tracheate 38. 



Anal processes large, swollen, filled with branched tracheae 48. 



38. Anal processes moderate, normal 39. 



Anal processes short, bud-shaped Grabhamia curriei. 



39. Pecten of the air tube with detached teeth ; tracheae broad 40. 



Pecten of the air tube without detached teeth 41. 



40. Lateral hairs of the first abdominal segments double ; detached teeth of comb 



well spaced Culex abfitchii. f 



Lateral hairs single ; teeth only a little detached Grabhamia vittata. 



41. Air tube long, slender, about 4 X * 42. 



Air tube short, stout, 3 X x or less...; 43. 



42. Tube scarcely 4X1; tracheae broad, not angled Culex cantons. 



Tube over 4 X J > tracheae narrow, angled Culex jitchii. 



43. Spines of comb thorn -shaped 44. 



Spines of comb thick with feathered tips Culex lazarensis. 



44. Anal segment almost completely ringed, tufts to base ; tube 2 X *■ 



• Culex aestivalis. 

 Anal segment distinctly not ringed ; tufts scarcely to base; tube 3 X l 45- 



45. Brush moderate, tufts short-stemmed, chitin mostly brown 46. 



Brush large, long stemmed, chitin mostly blackish Culex pullatus. 



46. Head with black lunate spots Culex cantator. 



Head without such spots 47. 



47. Comb scales with apical spine longer but not stouter than the subapical ones. . 



Culex canadensis. 

 Comb scales with apical spine stout and distinct, fringed by the smaller ones. 



Culex pretans. 



48. Tuft of tube within the pecten ; anal processes unspotted Culex atropalpus. 



Tuft of tube beyond the pecten ; anal processes spotted Culex varipalpus. 



49. Antennal tuft at the middle of the joint Culex restuans. 



Antennal tuft beyond the middle of the joint 50. 



50. Anal segment with tufts before the barred area Culex dyari. 



* G. sollicitans and C. trivittatus are very difficult to separate. Compare Smith's 

 figures, Ent. News, xv, pi. ix, 1904, and Bull. N. J. Agr. Exp. Sta., 1 71, pi. v, 

 I904. The former figure should be corrected by striking out the little tufts preced- 

 ing the barred area on the anal segment in Fig. 6. 



f Synonym, C. siphonalis Grossbeck. 



