Field Studies of the Non-Social Wasps 461 
mass. In so doing, she somehow dislodged one and it 
fell into a spider web below; she alertly recovered it, 
crammed it into the cell with precision and continued 
to pack the mass together for about five minutes, then 
flew out and brought one more spider which she depos- 
ited, almost filling the compartment. 
When she had again gone I forced five additional 
spiders into the cell; after a half hour she returned with 
another capture which she also forced in with great 
effort. It seemed that she had a fairly definite idea 
how many spiders were required, and bring them she 
must and would, regardless of unsolicited aid. This 
case is in sharp contrast to those which were content to 
seal their cells as soon as they found them full without 
asking any questions. 
On her next return, however, she brought a load of 
mud and closed the cell. As soon as she turned her 
back I opened it and removed one-third of the spiders. 
Upon her return she paid absolutely no attention to the 
broken cell or the missing spiders, but used her load of 
mud to again seal the cell. Once more I removed the 
seal and this time all of the spiders, in order to impress 
upon her more forcibly the seriousness of the injury. 
I accidentally broke a small piece out of the wall of the 
cell at the opening. The wasp returned, spread her mud 
over the opening, leaving the broken part untouched and 
quite ignoring the emptiness of the nest and the traces 
of vandalism. She discharged her duty always with a 
mechanical faithfulness; she seemed, nevertheless, exact 
—three loads of mud are usually required to seal a cell, 
and three loads she brought and applied properly before 
finally leaving the nest. 
Exp. XIX. When I arrived upon the scene, the fourth 
cell of a Sceliphron nest was half filled with spiders. 
