Field Studies of the Non-Social Wasps 347 
trated upon other insects; when again at liberty, twenty 
minutes later, I found the cell completely sealed, and then 
I ruefully realized that I had lost a rare opportunity to 
observe this species in action; to find whether she got the 
mud from elsewhere to seal the aperture, or in some way 
worked out the mud from various parts of the nests. For 
the next hour I watched the wasp busy at her work on 
various parts of the cell, principally at the newly made 
plug, in a very interesting manner. With her jaws she 
would scrape very energetically about the rough wall of 
the shanty, trying apparently to remove some of the sur- 
face of the wood, but in reality she was scraping together 
whatever she could get (often it was mostly dust and spi- 
der web) which she worked in her jaws on her way back to 
the nest a few inches away. When she reached the nest 
the mouthful was usually applied to the plug which had 
just been placed. She would press the small ball of 
dusty web against the plug, flex her abdomen directly 
under her mouth, emit a tiny globule of water apparently 
from the anus, and, with the flat-iron movement that 
we have elsewhere described for Pompiloides tropicus, 
Smooth and rub the material into the plug. This she 
did repeatedly. The rubbish she garnered was a motley 
mass; it was chiefly dust and spider web, with occa- 
Sional small splinters, bits of disintegrated insects and 
vegetation, which, combined with the added moisture, 
was worked into the nest. Not all of these reinforce- 
ments were directed solely to the plug, but many appli- 
cations were placed promiscuously about the nest. 
To see something entirely new in waspdom, and to 
See it done repeatedly, was indeed enough to hold one 
alert to catch every detail. To be sure, we had previ- 
ously discovered that a near relative, Pompiloides 
‘ropicus, likewise bends the abdomen under the body 
