278 THE HUMBLE-BEE 



Physocephala rufipes. Mr. E. E. Austen of the British 

 Museum has kindly examined the pupa that developed 

 from a large dipterous larva that I found inside the 

 abdomen of a queen of B. terrestris, stung to death on 

 Jul\- 24, 1912, and has found it to belong to one of 

 the Conopidae, " very probably to the species known as 

 Physocephala rufipes, Fabr., which is parasitic in the 

 abdomen of the imago of B. terrestris as well as in that 

 of other species of Bombus. It appears that when the 

 parasite reaches the final larval or pupal stage the host 

 frequently, if not always, perishes." The queen was one 

 bred the previous year, and was taken with her nest, in 

 which the first workers were about to hatch, on July 14. 

 The day before she was killed I noticed that she was 

 breathing at a slower rate than normal, and she had laid 

 no eggs for at least two weeks. 



