198 
BRITISH BEES. 
porting themselves upon any flowers that may he 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 Andrews , 
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 lame, 
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 antenme, 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 
