PROC. ENT. SOC. WASH., VOL. 22, NO. 7, OCT., IQ2O Kio 



In determining the sex of bumblebees I have found the shape 

 of the tarsal claws, first noted by E. T. Cresson, 1 to be very con- 

 venient. The claws are bifid in both sexes, but in the females 

 (queens and workers) the inner tooth is short, usually not more 

 than half the length of the outer, though occasionally somewhat 

 more, but always shorter than the outer. In the males, on the 

 other hand, the outer and inner teeth are of equal length. It is 

 as though, in the females, the claw had been cut from the inside, 

 short of the apex, while in the males, it had been cut, split, rather, 

 from the very tip. This character holds good for all species I 

 have examined. Unfortunately there is no way known at pres- 

 ent to distinguish workers from queens, save relative size, the 

 workers always being smaller. But in some cases it is a question 

 whether the specimen is a small queen or a large worker. 



This paper is based on specimens brought together by numerous 

 collectors, in addition to the writer. The material is chiefly in 

 the collections of the National Museum, the Biological Survey 

 and the author. 



The species occurring in this vicinity may be separated by the 

 following keys. 



Queens. 



1. Interaler band or black hair between the wings 7 



No interaler band 2 



2. Lower half of pleura black perplexus 



Pleura yellow to bases of legs '. . . 3 



3. Abdomen with more than half the second segment yellow 5 



Abdomen with not more than half the second segment yellow 4 



4. No yellow pile beyond the first segment impatiens 



Some yellow pile on second segment, never more than half. . . .bimaculatu* 



5. Malar space distinctly longer than it is wide at apex vagans 



Malar space not distinctly longer than it is wide at apex 6 



6. Ocelli large, placed well below supraorbital line, lateral ocelli nearer the 



eye margins than to each other separatus 



Ocelli small, near supraorbital line, lateral ocelli not nearer the eye 



margins than to each other affinis 



1 . Abdomen with first four dorsal segments yellow fervidus 



Not so colored 8 



8. First two dorsal abdominal segments yellow fraternus 



Usually with yellow pile on first three segments, first sometimes black. . .0 



9. Ocelli large, placed well below supraorbital line. uuricomus 



Ocelli small, placed near the supraorbital line peiinsylvanit-us 



Workers. 



1 . No interaler band 2 



1 Proc. Ent. Soc. Phil., Vol. II, 1863, p. 84. 



