162 MESSRS. C. HORNE AND F. SMITH ON HYMENOPTERA 
removal of a lock, a hollow between bricks, or between the wall and door-frame. 
Sometimes a roughness or slight depression in the floor is the unfortunate selection, 
where the first passer by will crush the construction, in which case the patient creature 
will rebuild it three or four times, and at last, in despair, abandon the locality; thus 
on one occasion I observed a cell built in the corner of the door-frame of a bath-room, 
so that it must be crushed every time the door was closed. The room was used at least 
once a day; and six times was the cell completely destroyed; it then abandoned the 
position. This was in October 1867 ; and I rather think that it ceased building merely 
in consequence of its season for cell-building having expired. 
Sometimes each cell is separately constructed; at others one is placed over another ; 
whilst I have observed them, as hereinafter described, build a mass of cells, as in the 
case of the corner of a room being selected. 
The building of these cells is very regularly conducted, and they are generally placed 
parallel to the ground. A line of pellets of mud, the base of the cell, is first put down, 
and each pellet is worked nicely and smoothly with the jaws, assisted apparently by the 
feet, so that, as the work is performed very quickly, the joins are hardly perceptible. 
Having finished off its work with one pellet, it stands over it, looks at it with com- 
placency, walks around it, pats it approvingly with its antenne, and at last, being 
satisfied, flies off for more material. 
I have reason to think that generally but one sex works at nest-building; for often, 
when I have captured an insect at work, no other has come to complete the structure. 
A cell takes about a day to make, the insect working assiduously as long as daylight 
lasts. As the walls rise, layer by layer, they are contracted until they meet in an arch, 
the insect meanwhile carefully smoothing and plastering the interior as the work 
proceeds. 
The next employment is the filling of the cell with food for the young grub. On 
one occasion only I observed green caterpillars being stored, although small field-spiders 
are the regular storing-food. 
The egg would appear to be deposited on the body of the first spider placed in the 
cell. This would lead one to infer that the female is the worker. 
Twenty spiders are sometimes packed away; and the egg or young grub of the insect 
has always been found by me on the lowest one when I have opened a cell directly 
after it has been closed up, which closing is effected directly the structure is well filled. 
Ordinarily, on one cell being finished another is begun alongside, as little space being 
lost as possible ; and in this way four, five, or six cells are made. 
Meanwhile the egg is hatched, and the young grub sucks out, one by one, the juices 
of the comatized spiders, until being fully grown and its stores finished, it spins its 
strong cocoon of fine agglutinated silk and changes into the pupa-state. In this it 
remains for periods varying from one to five months according to season. 
When the time for emerging arrives, the cap of the pupa-case gives way to the jaws 
