162 BRITISH APHIDES. 



spouding size, while the females devour other species 

 of greater bulk," and then he remarks, " lam surprised 

 that no allusion should have been made by Dr. Giraud, 

 beyond this casual notice, that the mother sometimes 

 separates the sexes, giving less food to the males, which 

 are usually smaller, and more to the females, which are 

 larger, according to their respective requirements." 



Instead of these selections being exceptional cases, 

 Sir Sidney Saunders contends that " this separation of 

 the sexes is the ordinary and invariable rule in all cases 

 where these briar cells are constructed in serial 

 sequence ; whether among the Crabronidse, the Andre- 

 nidge, the Eumenidse, or Apidas, the lower cells, up 

 to a certain range, being always tenanted by females, 

 and the upper by males ; the former retaining their 

 adipose condition longer, and being slower in attaining 

 maturity than the latter." Thus, in inverse ratio to 

 the period of their respective occupancy, the males 

 from the outermost cells, constructed last, are ready to 

 emerge first. We may say with Giraud that nothing 

 is more varied than the industry of these nesting 

 species. 



Each constructs its cells in the mode most appro- 

 priate to itself, and determines with remarkable preci- 

 sion the quantity of food necessary for the nourishment 

 of the larvjB of the generation to come — a generation, 

 be it remembered, that the mother can never see.* 



Thus it is, that when the provisions are exhausted, the 

 larvae have no further wants ; they remain in an inac- 

 tive condition, and often for a protracted period, until 

 they transform into the pupal and final winged states. 



Nevertheless, whatever may be the means emploj-ed 

 by the parents in constructing these curious galleries 

 and cells, no species can wholly escape the attacks of 

 its peculiar parasite — nothing can hinder their mission 

 to keep a just balance between the increase and the 



* Perhaps she is satisfied with the contemplation of the immortality 

 she creates for herself, in the eiforts she makes towards the development 

 of her race yet to come! — Vide 'Nineteenth Centm-y Review,' July 

 number, 1877, p. 836, et scq. 



