The Mason-bees 



the one case, the cylindrical form, the creamy- 

 white colouring and the little nipple constitu- 

 ting the head reveal to us the larva of the An- 

 thrax, which does not concern us at present; 

 in the other, the general structure and appear- 

 ance betray the grub of some Hymenopteron. 

 The Mason's second exterminator is, in fact, 

 a Leucospis {Leucospis gigas, Fab.), a mag- 

 nificent insect, striped black and yellow, with 

 an abdomen rounded at the end and hollowed 

 out, as is also the back, into a groove to con- 

 tain a long rapier, as slender as a horsehair, 

 which the creature unsheathes and drives 

 through the mortar right into the cell where 

 is proposes to establish its egg. Before occu- 

 rring ourselves with its capacities as an inocu- 

 lator, let us learn how its larva lives in the 

 invaded cell. 



It is a hairless, legless, sightless grub, easily 

 confused, by unexperienced eyes, with that of 

 various honey-gathering Hymenoptera. Its 

 most visible characteristics consist of a colour- 

 ing like rancid butter, a shiny and as it were 

 oily skin and a segmentation accentuated by a 

 series of marked swellings, so that, when 

 looked at from the side, the back is very 

 plainly indented. When at rest, the larva is 

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