DAUBER WASPS. 375 



substances, such as a tin-tack and a piece of worsted, into the cell. 

 The insect proved herself equal to the occasion, filled up the holes, 

 and pulled out both the tack and the worsted. The next point 

 was to watch a nest from its foundation, and to see how it was 

 built. The insect always went off, was absent for about a minute, 

 and then returned, bearing in her jaws a lump of clay larger than 

 her own head. The clay was perfectly plastic, and could be 

 spread at once. The method by which the cell is formed must 

 be given in the author's own words : 



"About this time (August 18) the other species of Pelopseus be- 

 gan to be busy fabricating their artful thimble-shaped nests. 



" It is difficult to convey by words an idea of their mode of 

 working. The commencement of a cell, was by laying down the 

 load and working it into an oval ridge, one extremity of which 

 was to be the apex of the thimble cell. The next load was laid 

 on the ridge, but so as to be higher at the apex than at any other 

 part, and made slightly concave. When the top was made, the 

 work proceeded regularly by additions to the edges, which were 

 smoothly laid on, and always in the same slanting direction that 

 had been given at first, by raising one end of the incipient oval, 

 so that an unfinished cell in any state of progress appears to be a 

 -cylinder cut off by a diagonal section. 



"This is not casual, but invariable, as the ridges remaining 

 plainly mark the precise limits of every load. 



" When a little more in length is finished than suffices for a 

 single cell, the work ceases for a while, an, egg is laid in the bot- 

 tom, though this end is generally uppermost, and spiders are 

 brought in. This species usually, not always, selects a very beau- 

 tiful species of Tetragnatha, bright green with white spots ; and 

 it is worth remarking that spiders are carried both with the jaws 

 and feet, one of the fore legs of the spider being grasped in the 

 mouth, while the body is held under that of the fly, and sustained 

 by the anterior and middle legs and feet, the posterior pair being 

 extended behind, as usual during flight. 



" When the first cell is stocked, it is closed up by a transverse 

 partition of mud, and the thimble goes on increasing as before. 

 When finished, one will contain three or even four cells, and then 

 a new one is commenced, adjoining and parallel with it. In both 

 this and the other species, I believe that the inclosed grub eats 

 only the abdomen of the spiders (which are so stung as to be help- 

 less, but not dead), as the. cephalothorax and legs of each may 

 generally be found afterward in the cell." 



