DEVELOPMENT OF CHALCIDS 



323 



OVIPOSITION. 



The female Chalcid selects a cocoon containing an Aphi- 

 dius larva on the point of metamorphosis, but sometimes 

 a newly-transformed pupa may be chosen. The hyper- 

 parasite shows considerable excitement in her search, and 

 runs round the cocoon, tapping it eagerly with her antennae. 

 Finally she mounts upon it, facing the head of the aphid, 

 and, boring through the integument with its silk lining, she 

 deposits a single egg upon the upper surface of the body of 

 the Aphidius larva, as it lies curved head to tail within 

 the cocoon. The whole operation lasts from one to three 

 minutes. Only one egg is inserted at each oviposition, and 

 when more are found they are the result of different attacks. 

 The number of eggs laid by each female seems to be between 

 thirty and forty, but it is difficult to be precise on this point 

 as the insects will live for some days in captivity, and the 

 eggs in the ovarian tubes do not all mature at the same time. 



The Egg. 



The eggs of Asaphes and Pachycrepis are indistin- 

 guishal:)le from one another. They are white, elliptical bodies 



Text-fig. 1. 



Text-fig. 2. 



Egg of Asaphes vulgaris, 

 xlOO. 



Egg of Pachyneiiron sp. 

 XlOO. 



with a smooth chorion, having dimensions, -29 x -12 mm. 

 (Text-fig. 1). 



The single example of the egg of Pachyneuron was 

 long, oval, and slightly curved. On the concave side, the 



