The Mason-bees 



lower already hold the Osmia's cocoons, while 

 the upper contain the larva which has nearly 

 finished consuming its provisions and the top- 

 most show the victuals untouched, with the 

 Osmia's egg, another egg is fixed: an egg 

 egg, rounded at both extremities, of a trans- 

 parent white and measuring four to five milli- 

 metres^ in length. It lies slantwise, one end 

 of it resting on the food and the other stick- 

 ing up at some distance above the honey. 

 Now, by multiplying my visits to the fresh 

 cells, I have on several occasions made a very 

 valuable discovery. On the free end of the 

 Osmia's egg, another egg is fixed; an egg 

 quite different in shape, white and transparent 

 like the first, but much smaller and narrower, 

 blunt at one end and tapering into a rather 

 sharp point at the other. It is two millimetres 

 long by half a millimetre wide.- It is unde- 

 niably the egg of a parasite, a parasite which 

 compels my attention by its curious method 

 of installing its family. 



It opens before the Osmia's egg. The tiny 

 grub, as soon as it is born, begins to drain 

 the rival egg, of which it occupies the top 



^.156 to .195 inch. — Translator's Note. 

 2.078 and .019 inch. — Translator's Note. 

 246 



