78 BEES AND WASPS [OH. 



ground ivy and thistle in search of nectar. The 

 pollen-collecting apparatus of the females is in the 

 form of a dense brush of hairs, often very brightly 

 coloured, upon the under side of the abdominal 

 segments. 



The rare " cuckoo " bees of the genus Stelis are 

 parasitic upon some species of Osmia. 



We have in this country several other genera of 

 bees in which the pollen brush is situated as in 

 Osmia. Of these, Chelostoma contains two species, 

 both of which are so small that they are not very 

 likely to attract attention, though one of them, Ch. 

 campanularum, may often be seen in large numbers 

 hovering round and entering the flowers of the hare- 

 bell and various species of "Canterbury bell" in 

 gardens during June and July: both species fre- 

 quently are to be found in the evening asleep in the 

 recesses of the bell-shaped blossoms. The true leaf- 

 cutter bees of the genus Megachile are, however, large 

 and conspicuous insects, and often force themselves 

 upon our notice. The habit of using portions of 

 leaves for the construction of the nest is not entirely 

 confined to Megachile', for, as might perhaps be 

 expected, one species of Osmia, viz. fulviventris, is 

 stated on the authority of that excellent observer, 

 Mr R. C. L. Perkins, to cut out for this purpose 

 portions of slightly withered, yellowish leaves, though 

 not with the deftness of a Megachile, for a jagged, 



