XVIII A PARASITE— THE COCOON 255 



materials it would doubtless have used these scrap- 

 ings for its constructions, but I thought it better to 

 provide according to its tastes and give it sand. 

 Never did Bembex larva build with such sumptuous 

 material. I poured out for my prisoner sand for 

 drying writing, — sand well sprinkled with gilded 

 grains of mica, — before the opening of the bag, which 

 was in a horizontal position, suitable to the work 

 which would follow. The larva, half out of its 

 hammock, chose its sand almost grain by grain, 

 routing in the heap with its mandibles, and, if one 

 too bulky presented itself, it was seized and cast 

 aside. The sand being sorted, the larva introduced 

 a certain quantity with its mouth into the silken 

 fabric, then retired into its sack and began spreading 

 the materials in a uniform layer on the inner surface, 

 then glued together various grains and inlaid them 

 in the fabric, with silk for cement. The outer sur- 

 face was constructed more slowly. These grains 

 were carried singly and fixed on with silk gum. 



This first deposit of sand only concerns the 

 anterior part of the cocoon — that half which ends in 

 the opening. Before turning round to work at the 

 back part, the larva renews its store of materials and 

 takes certain precautions, so as not to be embarrassed 

 in its masonry. The sand heaped before the 

 entrance might slip inside and hinder the builder in 

 so narrow a space. The grub foresees this, and 

 glues some grains together, making a coarse curtain 

 of sand, which stops up the orifice, imperfectly indeed, 

 but enough for the purpose. These precautions 

 taken, the grub labours at the back part of the 

 cocoon. From time to time it turns round to get 



