THE HABITS OF EUMENES BELFRAGEI, CRESS 357 



The work of nest building proceeds without hesitation. The 

 mud brought at each load is applied immediately on the arrival 

 of the wasp. The first few loads are plastered around the grass 

 stem and blades and serve to anchor the prospective nest to 

 its foundation. The sixth load completes a flat circular disc, 

 vertical in position, firmly fixed to the grass. The seventh, 

 ninth, eighth and tenth loads are applied respectively to the 

 upper, lower and lateral edges of the disc and then pulled out. 

 There is now the first indication of the future cavity of the. 

 nest. Loads eleven, twelve and thirteen form another ring of 

 mud, each application lapping over the individual portions 

 previously applied, as is the rule in the nests of the Pelopaei. 

 Perhaps this avoidance of coincident joints adds to the strength 

 of the nest. 



The upper portion of the nest grows faster than the lower 

 until the point is reached in the upper portion where the neck 

 of the " bottle " is to be ; then the lower edge of the now rapidly 

 diminishing opening is built up until the opening is only 3 or 

 4 mm. in diameter. The neck and the rim are now put on with 

 the last three loads of mud. The neck has a lumen 2 mm. in 

 diameter. 



The wasp's manner of working is of interest. The work of 

 plastering on and smoothing down the mud is performed with 

 the mandibles and the forelegs, the other legs being used only 

 to hold on. The pellet of mud is placed on the desired spot 

 where it adheres (fig. 2), It is then rolled with the forelegs 

 and mashed with the mandibles, the motion continuing in one 

 direction as long as the quantity of mud will allow. Like all 

 movements of this wasp this spreading movement is perfectly 

 steady and devoid of any jerky motion characteristic of the 

 Sphecina. 



The mass of mud is now in the 'shape of a ribbon on the edge 

 of the wall of the cell. The mud must next be pulled up so 

 as to thin 1 it out to the normal thickness of the wasp's nest. 

 This is done by squeezing the mud between the head (mandi- 

 bles) and the forefeet, the feet on the outside and the head on 

 the inside of the nest (figs. 3 and 4). No exception to this rule 

 has been noted. Thus, to make a homely comparison, if the 

 human hand were to perform this task, the mud would be 

 molded between the thumb and the index finger. 



