11 EIME-HISTORY OF ZOMBUS 45 
The nest material is pushed out to make room 
for the growing comb, and there is always a space 
for the passage of the bees between it and the top 
of the comb. Over this space, and lining the inside 
of the nest material, a ceiling of wax is generally 
made in populous nests, the wax being worked into 
a thin sheet as in the coverings of the larve and 
the walls of the honey-pots. Provided there is 
room for it, this waxen canopy is always found com- 
pletely enveloping the top of the comb in populous 
colonies of 4. dafidarius, an underground-dwelling 
species that produces more wax than any other. 
Populous colonies of the underground species ¢erres- 
tris, lucorum, ruderatus, and hortorum generally suc- 
ceed in time in making complete canopies, but in the 
nests of the surface-dwelling species, which, one would 
imagine, specially need such a protection to keep 
out the rain, the waxen ceiling is, in most cases, 
incomplete or absent, and frequently consists only of 
a small disc of wax over the centre of the comb. 
B. derhamellus is particularly disinclined to com- 
mence building a ceiling ; in several very populous 
nests of this carder-bee no trace of one was seen. 
In order to watch what is taking place in my 
observation nests I have sometimes had to remove 
the waxen ceiling. In a populous colony of /afv- 
darius it has been entirely built again within two 
days, the construction commencing at the sides of 
the box, and the whole ceiling built from these with 
no other support but that of the bees constantly 
passing to and fro on the comb. 
