i DASYGASTRES- MASON-BEES PARASITES 43 



when the bee brings provisions to add to the stock, it carries 

 both honey and pollen ; in order to deliver these it begins by 

 entering head first into the cell and disgorging the honey, then 

 emerging it turns round, enters backwards and scrapes off the 

 pollen from its body. If after the honey has been discharged, 

 the bee be interfered with and gently removed to a slight dis- 

 tance with a straw, it returns to complete its task, but instead of 

 going on with the actions at the point at which the interruption 

 took place, it begins the series over again, going in at any rate 

 partially head first, although it has no honey to discharge, and 

 having performed this useless ceremony it then emerges, turns 

 round and adds the pollen. This illustration is in some respects 

 the reverse of what might have been expected, for the Insect 

 here does not continue the act at the interrupted point, but begins 

 the series of actions afresh. 



It would be reasonable to suppose that an Insect that takes 

 the pains to provide for the safety of its progeny by constructing 

 a complex edifice of cement, secures thereby the advantage of 

 protection for its young. But this is far from being the case. 

 Notwithstanding the cement and the thick dome of mortar, the 

 Chalicodoma is extremely subject to the attacks of parasites. 

 The work performed by the creature in constructing its mass of 

 masonry is truly astounding ; Fabre calculated from measure- 

 ments he made that for the construction and provisioning of a 

 single cell, the goings and comings of the bee amounted to 15 

 kilometres, and it makes for each nest sometimes as many as 

 fifteen cells. Notwithstanding all this labour, it would appear 

 that no real safety for the larvae is obtained by the work. Some 

 sixteen possibly more other species of Insects get their living 

 off this industrious creature. Another bee, Stelis nasuta, breaks 

 open the cells after they have been completely closed and places 

 its o\vn eggs in them, and then again closes the cells with 

 mortar. The larvae of this Stelis develop more rapidly than do 

 those of the Chalicodoma, so that the result of this shameless 

 proceeding is that the young one of the legitimate proprietor 

 as we human beings think it is starved to death, or is possibly 

 eaten up as a dessert by the Stelis larvae, after they have 

 appropriated all the pudding. 



Another bee, Dioxys cincta, is even more audacious ; it flies 

 about in a careless manner among the Chalicodoma at their 



