242 NATURAL HISTORY OF WASPS. 
after brood successively undertake the task of build- 
ing, replacmg the older wasps which, like their 
queen, are past the age for making paper. Thus a 
constant system of promotion is gomg on, those 
which have no longer the faculty of house-making 
betake themselves to the duties of house-keeping, 
and while the large young wasps, in full glandular 
vigour, maintain and enlarge the nest, the older 
shrunken wasps find full employment in satisfying 
the hungry mouths which peer out from the lower 
surface of the combs. 
While, under this regular system, the swarm is 
thriving, and fulfilling the duties of wasps by des- 
troying a vast amount. of insects—even more noxious 
than themselves some would say—and of rotten 
wood, preparation is made for the perpetuation of 
the species. The drones or male-wasps, and the 
perfect females, now make their appearance. The 
cells in which both of these are bred are taller and 
larger than the worker cells, especially those of the 
perfect females. Sometimes one of the lower combs 
is composed entirely of queen-cells, or a zone of 
these larger cells may be seen in the ordinary comb, 
their tall white domes overtopping the humbler 
abodes of the worker brood. It is said that these 
cells are never used more than once.* This state- 
ment is made on too good authority to be questioned, 
but the fact admits to a certain extent of explana- 
tion by the circumstance that when the male and 
female brood appear the season is advanced, and the 
store of eggs of the queen well nigh exhausted. 
The appearance of the males and females mdicates 
* Smith. ‘Catalogue of British Hymenoptera,’ 1858, p. 214. 
