ioo WASP STUDIES AFIELD 



obstructions, no two burrows were alike. Of course there 

 is some reason for Philanthus and Xylocelia metathoracicus 

 making a tortuous gallery in a clay bank which is full of 

 rocks, roots and rubbish; but here this extreme variety in 

 habit makes one think that either there is instability of the 

 species, or that so far as natural selection goes this point 

 is of no consequence to the species; hence a fixed habit 

 would be superfluous. We like to think of the staple form 

 of nest that all Ammophila pictipennis make as being fixed 

 by Natural Selection that this form of nest is in some 

 way best fitted for the needs of the species but in this 

 group no form has a particular advantage over the others, 

 so none are eliminated and thus none is selected. 



At noon (October 2) the mothers were all in their holes. 

 This may have been due to the cold autumn nights and 

 mornings. Later in the afternoon, when the sun shone 

 more directly upon the bank and warmed it, two of the 

 wasps were carrying in flies, hugging them under the body 

 in the usual way. 



In many cases we have found the prey at the bottom of 

 the burrow where it was being deposited as it was brought 

 in, but we have been unable to find out if the wasp completely 

 closes this burrow after the cell has been filled and then 

 makes another long burrow for the same purpose, or if 

 she makes and fills one chamber at the end of the burrow, 

 closes this and extends the burrow to form another, and so 

 on. It seems improbable that a new channel can be made for 

 each cell, for in the two days spent in this colony we never 

 witnessed the surface closing of a burrow. Furthermore 

 several finished cells were found suspiciously near to an 

 open burrow, and, in one nest opened, one such cell was 

 just at the point of a sharp angle of the burrow, which 

 would indicate that they are dropped down from the tunnel. 



One interesting item about this species is the tenacity 



