64 BEES AND WASPS [OH. 



one hundred and twenty different kinds being known. 

 They are grouped by entomologists into ten different 

 genera of which Andrena, Halictus, Nomada and 

 Sphecodes contain the greatest number of species; 

 the two last are "cuckoo" bees, laying their eggs in 

 the nests of the two preceding. Andrenas are the 

 "hosts" for most of the Nomads ; Halicti for the 

 Sphecodes. 



Very many of the bees of the genus Android 

 occur early in the year, being on the wing in March, 

 April and May : they often abound upon the blooms 

 of the sallows, and of blackthorn. Some of these 

 early species have a second brood which appears later 

 in the summer, while a few are to be seen only in 

 July and August. Of these last A. argentata is 

 extremely common on the heaths of Surrey and 

 Hampshire where it may sometimes be seen in hun- 

 dreds flying over and visiting the heather bells : it is 

 a small bee about a third of an inch long and is 

 clothed with pale grey, almost silvery hair. All the 

 Andrenas are hairy bees, and their abdomens are 

 rather flat along the back : in general appearance many 

 are like the honey-bee, but considerably smaller. 

 One of the most noticeable of this group is a bright 

 brown, almost red little bee, named A. fulva. In 

 some places this handsome little insect is very abun- 

 dant and is sure to attract attention not only by its 

 bright colouring, but also by its habit of burrowing 



