Field Studies of the Non-Social Wasps 343 
genera Macromeris, Paragenia, and Pseudagenia and 
others [of the Psammocharidae] are mason wasps, hav- 
ing advanced beyond the digging stage still adhered to 
by the majority of the family. They build cells of clay 
or other earth-like material; they may construct these in 
sheltered or unsheltered places above the ground, more 
rarely in burrows.’’ As Williams says, ‘‘having advanced 
beyond the digging stage,’’ to a mud-daubing cell-maker, 
So certain individuals of the species P. mellipes, in their 
cell-making, have gone a step forward in eliminating the 
carrying of the building materials. We find that in P. 
mellipes this labor-saving method of using materials at 
hand, or rather of finding the building materials in the 
Shape of a lump of mud plastered on the wall, and then 
fashioning it into cells, entails the habit of carrying 
water. This method, when first I discovered it, greatly 
surprised me, since I thought only the Odynerus wasps, 
and Anthophora bees were capable of so ingenious a 
method. Since then I have found this same feat done 
by Chalybion caeruleum, which shows at least that this 
habit can penetrate families regardless of structure (tax- 
onomy). That this water-carrying habit is more deep- 
Seated in the genus than the newly acquired habit of 
using mud nests already at hand is evidenced by the fact 
that Williams tells us of a species in the Philippine 
Islands which follows this method, showing that habit 
persists in spite of remoteness. Another habit that dis- 
tance has not obliterated is the method of using the 
dorsal tip of the abdomen, flexed under the head, as a 
rounded smoothing tool, in fashioning the nest. This 
habit we observed also in Pompiliodes tropicus,* and in 
Williams’ report he records this habit for three species 
of Pseudagenia, 
“Wasp Studies Afield, p. 54, 1918. 
