352 WASP STUDIES AFIELD 



re-entered the hole without turning around. An old bee co- 

 coon she pulled out bodily and cast aside thus. Here we 

 see an additional activity of this wasp; enlarging holes to 

 make them suitable for her habitation. 



Thus far in the observations, we had never seen one of 

 these wasps actually cutting wood, but in all of the instances 

 mentioned above and a number of others, they had merely 

 utilized the old holes of carpenter-bees or other borers. 

 Hence we were growing suspicious that these so-called car- 

 penter-wasps are not wood-cutters at all. At this juncture 

 our surmise was strengthened by finding a nest in the hol- 

 low roller-holder of an old iron bed-post on a junk-heap. 

 Of course we could not open up the nest to examine its 

 structure, but with the forceps we removed the caterpillars, 

 six in number. Two were of the species mentioned here- 

 tofore, and four were of two other species not noted before ; 

 a mishap prevented their identification, but this record will 

 show that M. qiiadridens uses more than one species of 

 prey. 



On July 25 one of these wasps was noticed in the out- 

 door laboratory, where she had appropriated an old nest 

 of the Pelopoeus mud-dauber. This nest was lying on the 

 shelf, and had been used also by a Trypoxylon clavatum for 

 nidus. The cell in the top row of the nest was empty and 

 open, and Monobia had enormously enlarged its opening. 

 It already contained two caterpillars and the egg was hang- 

 ing on its thread. This nicely shows that M. qiiadridens 

 does not first provision the nest and then oviposit, as do 

 some Hymenoptera, but that she lays the egg before or 

 during provisioning. That night she slept in the cell with 

 her face toward the opening, and by July 29, when I re- 

 turned to the farm, she had completed and sealed the cell. 

 Between August 5 and 15 one male wasp emerged. The 

 cell when opened contained no evidence of a cocoon, but 



