The Theory of Parasitism 



part, high up above the honey. The exter- 

 mination soon becomes perceptible. You can 

 see the Osmia's egg turning muddy, losing 

 its brilliancy, becoming limp and wrinkled. 

 In twenty-four hours, it is nothing but an 

 empty sheath, a crumpled bit of skin. All 

 competition is now removed; the parasite Is 

 the master of the house. The young grub, 

 when demolishing the egg, was active enough: 

 it explored the dangerous thing which had to 

 be got rid of quickly, it raised its head to 

 select and multiply the attacking-points. 

 Now, lying at full length on the surface of 

 the honey, it no longer shifts its position; but 

 the undulations of the digestive canal betray 

 its greedy absorption of the Osmia's store of 

 food. The provisions are finished in a fort- 

 night and the cocoon is woven. It is a fairly 

 firm ovoid, of a very dark-brown colour, two 

 characteristics which at once distinguish it 

 from the Osmia's pale, cylindrical cocoon. 

 The hatching takes place in April or May. 

 The puzzle is solved at last: the Osmia's 

 parasite is a Wasp called Sapyga punctata, 

 V. L. 



Now where are we to class this Wasp, a 

 true parasite in the strict sense of the word, 

 247 



