6o THE HUMBLE-BEE 



in 



upon the bounty of the Bombi. This view was 

 upheld by Hoffer, who, in 1889, published a mono- 

 graph on the Psithyri 1 in which he recorded ob- 

 servations of his own in Styria supporting it. But 

 my observations have shown that at least two of 

 the species of Psithyms are deadly parasites upon 

 the species of Bombus in whose nests they breed. 

 In the years 1891 to 1894 I dug up many nests 

 of Bombus lapidarius containing its parasite 

 Psithyms rupestris, and of B. terrestris containing 

 its parasite Ps. vestalis, and I noticed that in every 

 case the Psithyrus female had taken the place of 

 the mother of the colony, whose remains I gener- 

 ally found lying under or near the nest. Investiga- 

 tion showed that it is the practice of the Psithyrus 

 female to enter the nest of the Bombus, to sting 

 the queen to death, and then to get the poor workers 

 to rear her young instead of their own brothers 

 and sisters. 2 



The way in which the Psithyrus queen proceeds 

 in order to ensure the success of her atrocious work 

 has all the appearance of a cunning plan, cleverly 

 conceived and carried out by one who not only is 

 a mistress of the crime of murder, but also knows 

 how to commit it at the most advantageous time 

 for herself and her future children, compelling the 



1 Die Schmarotzerhummeln Steiermarks, by E. Hoffer (Graz. Nat. Ver.), 

 18S9. 



- An outline of the life-history of Psithyrus here described was given in my 

 privately published booklet The Humble-bee, its Life- History a/id How to 

 Domesticate It, in 1892. See also Amateur Naturalist, Croydon, of May 

 '^93. P- 38 ; and Hymeiwptera Aculeata qf the British Islands, by E. Saunders, 

 1896, p. 354- 



