INSECUTOR INSCITI^ MENSTRUUS 61 



Aedes impiger Walker (decticus Howard, Dyar & Knab). • 

 True to its habits in the Yukon Territory, this species was 

 found associated with Aedes cataphylla Dyar {prodotes Dyar), 

 in lesser numbers, occurring in the two large breeding-places 

 discovered to the extent of about 10 per cent of the number. 



Little Truckee River, California, May 7, 8, 9, 1921 (H. G. 

 Dyar). 



Lake Tahoe, California, May 7 to 12, 1921 (H. G. Dyar). 



ILLUSTRATIONS OF THE MALE HYPOPYGIUM 

 OF CERTAIN SABETHIDS 



(Diptera, Culicidce) 



By HARRISON G. DYAR 



Sabethinus undosus Coquillett (Plate II, fig. 3). 



Sabeihoides undosus Coquillett, Proc. Ent. Soc. Wash., vii, 186, 

 1906. 



Sabethinus intermedius Theobald (Mon. Culic, iv, 619, 

 1907) must be close to undosus, the brilliant apple-green of 

 mesonotum, as described, agreeing perfectly. Theobald's un- 

 usually lucid reference to the male genitalia, "claspers ending 

 in a broad plate with one side fimbriated," would seem almost 

 decisive (compare fig. 3). However, I learn from Mr. F. W. 

 Edwards that there is no trace of white on the under side of 

 the fifth hind tarsal joint, which marking is present in undosus. 

 Formerly we relied on the supposed presence of scales on the 

 postnotum to distinguish this form, but Dr. and Mrs. Bonne 

 say that there are no scales in any of the species in this position. 

 5. intermedius has been credited to Lutz in Bourroul (1904), 

 but no description is known to me before that of Theobald. 



Sabethinus aurescens Theobald (Plate II, figs. 1, 2). 



Sabethinus aurescens Theobald, Mon. Culic, iv, 622, 1907. 

 Sabcthes identicus Dyar & Knab, Journ. N. Y. Ent. Soc, xv, 

 207, 1907. 



In the monograph we give what purports to be a figure of the 

 male hypopygium of this form (Plate II, fig. 6), but a re- 

 examination of the material shows that both this figure and 



