25 



reached in an elaborate cocoon spun by the male around the 

 prey and replacing the latter as an object of attraction. This 

 replacement is self-evident in many examples studied by 

 Mr. Hamm ; for in these there was nothing but an empty 

 cocoon, the prey having probably been lost during the process 

 of construction. 



There are strong reasons for the belief that the last stage 

 has been reached through the second and the second through 

 the first, but this inference must not be extended further and 

 made to apply to the species themselves. 



Empidae and their prey in relation to courtship. 



I. Prey devoured by both sexes independently of pairing. 



A. Tachydromia {Tachydrominae). Prey very nearly always 

 Dipterous and often belonging to the genus Tachydromia, 

 perhaps sometimes to the same species as the captor. The 

 female in copula has very rarely been found with prey. 1908 — 

 ninety catalogued specimens (or mounts), of which 17 were 

 captured by Mr. C. H. Hamm ; 1909 — eighty-six, of which 

 2 were captured by Mr. C. H. Hamm ; 191 1 — thirty. 



B. Hybos {Hybotinae). Prey generally Hymenopterous. 

 1908 — eighty-four, of which 26 were captured by Mr. C. H. 

 Hamm; 1909 — two; 191 1 — six. 



C. Empis trigramma, punctata, and scutellata {Empinae). 

 A little group of related species with habits very different 

 from those of the rest of the genus so far as it has been studied. 

 1 909 — sixty-three. 



II. The prey provided by the male is devoured or sucked 

 by the female during copulation. 



A. Pachymeria {Empinae). The prey always Dipterous. 

 3908 — one hundred and ten ; 1909 — one hundred and seventy- 

 eight. 



B. Rhampliomyia {Empinae). The prey nearly always 

 Dipterous. 1909 — three; 1910 — two hundred and fifty; 

 1 91 1 — sixty-five. 



A 7 



