THE EUMENIDAE 341 



Creve Coeur Lake, digging up mouthfuls of mud. Later 

 in the day another individual was seen, at the same place, 

 doing precisely the same thing. We suppose it was carry- 

 ing mud to make partitions and plugs in its burrow some- 

 where, perhaps in wood. Several others were entering 

 holes in old logs piled a short distance away. Some of them 

 were digging in the wood. One in particular entered a 

 shallow hole and, with the body partly protruding, turned 

 itself around so that it was inverted, and cut away the wood 

 at the ceiling of the burrow. Hence we see that they do not 

 use old tunnels of other insects, but mine their own or 

 enlarge those already at hand. 



We found 9 that this species makes good use of the old 

 cells of mud-daubing wasps. They use these old cells with- 

 out modification, filling them with caterpillars for their 

 young and then sealing the aperture with mud. Ashmead 

 cites Walsh, who saw one nest-building in a spool. 



Not alone does this wasp use the tunnels in wood with or 

 without modification ; she also digs burrows of her own. In 

 a small clay bank, protected overhead by a porch, three 

 specimens of this wasp were seen at work as early as June 

 28. As the season advanced, others appeared. 



The interesting feature of this bank was that its face 

 was completely riddled with the old tunnels of a mining- 

 bee, Entechma taurea Say (see fig. 68), any one of which 

 would have made an ample domicile for this wasp. Instead 

 of appropriating one of these, however, she always built 

 her own tunnels in the clay bank, although in so doing she 

 often broke into the barrel-shaped cells left by this bee. 



One of these wasps was seen in the morning bringing in a 

 caterpillar and in the afternoon sealing the cell with a plug 

 of wet earth. The burrow, when opened, was found to have 

 two cells, separated by a partition of mud. The tunnel was 



9 Journ. Animal Behavior 6 : 27-63. 1916. 



