Ecological and Behavior Notes 25 



yellow clay. The nest of S. pictipennis is clearly and in- 

 variably 'Tj" shaped, but in these two cases the nests 

 looked more like those of P riononyx atratum. The bot- 

 tom cham])er was three-quarters of an inch below the 

 surface of the ground; the length was li/^ inches, and 

 the diameter was 3/16 inch. I could not ascertain 

 whether S. argentatus always makes this type of nest, or 

 whether these two mothers, when they dug into the sand 

 and struck the hard clay, sidled along horizontally and 

 made the nest such as we describe, instead of abandon- 

 ing the attempt or working through the tough clay to 

 make an ''L" shaped burrow. Besides S. pictipennis, 

 we know that S. procera make nests of that conventional 

 form. Both of these nests contained a caterpillar each 

 of the same species of Geometridae [Fracker], and each 

 caterpillar had a wasp egg on the left side of the body 

 a little below the center. Both caterpillars were dead, 

 but these were dug up four days after the nests had been 

 sealed. 



These wasps were out late in the season. On October 

 18, 1918, about half a dozen of them were seen at Her- 

 culaneum. Mo., and the next day three more were ob- 

 served along the roadside to Hematite, one of which was 

 trundling her caterpillar home at that unusual date. The 

 method of carrying the caterpillar is of some interest, 

 since in Wasp Studies Afield we have stated that the 

 method of certain Sphex (Ammophila) in carrying the 

 caterpillar with the dorsal surface toward the ground 

 was no mere accident, but was a very effectual improved 

 method. In this specimen of S. argentatus it was clearly 

 demonstrated to be a fact. 



On three separate occasions, when the wasp left her 

 caterpillar because of my too close proximity, and the 

 caterpillar in curling up its body rolled on its side, in 

 each instance she mounted it, marched on with it for a 

 time with its side to the ground. After pulling it along 

 in this difficult position for a foot or so, she each time 



