288 INSECT ARTIZANS AND THEIR WORK 



deposited an egg in the pollen-mass. This egg 

 hatching soon after the cell has been sealed up, 

 the Dioxys larva has avoided further trouble by 

 eating the Mason's egg and then consuming the 

 provisions. High as is the percentage of destruction 

 in the case cited, it is not the worst, for Fabre says 

 he has frequently examined nests without finding a 

 single cell that had not been attacked by one or 

 other of these parasites. 



Colletes is a small hairy bee, in general appear- 

 ance somewhat like the Honey Bee. It burrows 

 into hard sandy banks, and in the burrows constructs 

 its cells. There is a small group ,of other bees 

 named Epeolus which exist solely at the expense 

 of Colletes, and they have adopted a rather " cute " 

 way of locating their victim's nest without the 

 fag of searching for it. Epeolus variegatus has 

 discovered that Colletes daviesanus has a fondness 

 for the pollen of tansy. So Epeolus frequents the 

 tansy flowers, and when Colletes comes along to 

 get another supply of pollen it is easy to shadow 

 her to her nest, get in as soon as her back is turned, 

 and leave the fatal eggs behind. 



Then there are several species of Coelioxys of 

 similar marauding habits, and they prey chiefly 

 upon the Upholsterer Bees (Megacbile), also upon 

 Osmia. Friese says that when Coelioxys sees the 

 rightful owner of the nest returning with a fresh 

 supply of pollen she seeks to get out of the way 

 and not be seen ; but it is a characteristic of all 

 these burglars not to act in a way that is likely 



