44 HYMENOPTERA CHAP. 



work, and they do not seem to object to its presence unless it 

 interferes with them in too unmannerly a fashion, when they 

 brush it aside. The Dioxys, when the proprietor leaves the cell, 

 will enter it and taste the contents ; after having taken a few 

 mouthfuls the impudent creature then deposits an egg in the 

 cell, and, it is pretty certain, places it at or near the bottom of 

 the mass of pollen, so that it is not conspicuously evident to the 

 Chalicodoma when the bee again returns to add to or complete 

 the stock of provisions. Afterwards the constructor deposits its 

 own egg in the cell and closes it. The final result is much the 

 same as in the case of the Stelis, that is to say, the Chalicodoma 

 has provided food for an usurper ; but it appears probable that 

 the consummation is reached in a somewhat different manner, 

 namely, by the Dioxys larva eating the egg of the Chali- 

 codoma, instead of slaughtering the larva. Two of the Hymenop- 

 tera Parasitica are very destructive to the Chalicodoma, viz. 

 Leucospis gigas and Monodontomerus nitidus ; the habits of which 

 we have already discussed (vol. v. p. 543) under Chalcididae. 

 Lampert has given a list of the Insects attacking the mason-bee 

 or found in its nests ; altogether it would appear that about 

 sixteen species have been recognised, most of which destroy the 

 bee larva, though some possibly destroy the bee's destroyers, and 

 two or three perhaps merely devour dead examples of the bee, or 

 take the food from cells, the inhabitants of which have been 

 destroyed by some untoward event. This author thinks that 

 one half of the bees' progeny are made away with by these 

 destroyers, while Fabre places the destruction in the South of 

 France at a still higher ratio, -telling us that in one nest of nine 

 cells, the inhabitants of three were destroyed by the Dipterous 

 Insect, Anthrax trifasciata, of two by Leucospis, of two by Stelis, and 

 of one by the smaller Chalcid ; there being thus only a single 

 example of the bee that had not succumbed to one or other of 

 the enemies. He has sometimes examined a large number of 

 nests without finding a single one that had not been attacked by 

 one or other of the parasites, and more often than not several of 

 the marauders had attacked the nest. 



It is said by Lampert and others that there is a passage in 

 Pliny relating to one of the mason-bees, that the Eoman author 

 had noticed in the act of carrying off stones to build into its 

 nest ; being unacquainted with the special habits of the bee, he 



