BURGLARS 287 



advantage of age and bulk, overpowers Osmia and 

 eats him. 



The Nomad Bees (Nomada) in a similar way 

 enter the earth-burrows of Andrena (page 21), and 

 deposit there eggs in her uncompleted cells, with 

 a similar result ; and Melecta plays much the same 

 part in the burrows of Anthophora. 



The Mason Bee (Chalicodoma), previously referred 

 to, has a hard struggle to maintain its existence, 

 for no fewer than sixteen different species of burglars 

 have been found in its cells, including Leucos-pis. 

 A few of these, it is suspected, may turn out to be 

 detectives on the track of the burglars, but when 

 allowance has been made for that probability the 

 effect of the industry of the others in checking the 

 reproduction of the hard-working Mason are 

 appalling. 



Fabre broke up one of the masses of masonry 

 which comprised nine cells, and found only one 

 that had not been criminally entered by an enemy. 

 In these eight cells the proper occupant had either 

 been eaten by the burglar or had been starved to 

 death owing to the interloper having consumed its 

 stores of food. Three had fallen victims to the 

 grub of a two-winged fly (Anthrax tr if as data), the 

 others to enemies of its own class, including Leu- 

 cospis (two), Stelis (two), and Dioxys (one). 



The latter Chalcid has been noticed flying around 

 and making observations during the building opera- 

 tions ; and it is believed that when the Mason has 

 gone off for a further supply of pollen, Dioxys has 



