198 BRITISH BEES. 



porting themselves upon any flowers that may be ad- 

 jacent, and they are especially fond of Ragwort. Their 

 prevalent colours are black and red, the latter occurring 

 only on the abdomen in different degrees of intensity 

 and extension, sometimes occupying the whole of that 

 division of the body, and sometimes limited to a band 

 across it. Much difficulty attaches to the determina- 

 tion of the species from the characters which separate 

 them being extremely obscure, for it is not safe to de- 

 pend upon the differences of the arrangement of colour 

 upon them, as it varies infinitely ; nor can their relative 

 sizes be depended upon as a clue, for in individuals 

 which must be admitted to be of the same species, size 

 takes a wider extent of difference than in almost any of 

 the genera of bees. St. Fargeau, who maintains the 

 parasitism of the genus, accounts for it by saying that 

 in depositing their eggs in the nests of the Andrencs, 

 Halicti, and Dasypoda, the Sphecodes resorts to the 

 burrows of the species of these genera indifferent to 

 their adaptation to its own size, and thus from the 

 abundance or paucity of food so furnished to its larvae, 

 does it become a large or a small individual. West- 

 wood says the species are parasitical upon Halictus. 

 Latreille says they are parasites. They are certainly 

 just as destitute of the pollinigerous apparatus as the 

 preceding genus. Mr. Thwaites once thought he had 

 detected a good specific character in the differing lengths 

 of the joints of the antennae, but I believe he never 

 thoroughly satisfied himself of its being practically 

 available. At all events great difficulty still attaches to 

 their rigid and satisfactory determination. There is an 

 array of entomologists who deny their being parasites. 

 Mr. Kirby says they form their burrows in bare sections 



