278 B. GRASSI AND A. SANDIAS. 
[As a rule a certain number of both sexes become mature at 
the same time, and the males invariably take flight two or 
three hours later than the females.| Further details on the 
subject of swarming will be found in the later section on Habits. 
Soldiers and soldier larve are to be found the whole year 
round, but only small soldiers are present in nests under two 
years old. 
6. Duration of Development, of Life, &c. 
These matters are very difficult to ascertain, but the follow- 
ing facts are certain : 
1. Owing to the interruption of development from November 
to April, individuals in the same stadium may be of different 
ages. 
2. Eggs which pass the winter in the gastrula stage will 
give rise in the following summer at most to soldiers with 
15-jointed antenne, or to larve with similar antennze, and with 
or without very short wing-rudiments. These larve become 
perfect insects and swarm in a later summer. 
These conclusions are the result of minute examinations of 
numerous small or orphaned nests, &c., some of which I shall 
proceed to record. 
By searching in the situations which have been described 
as the points of origin of new nests, from August to April, 
some two to twenty perfect insects, with the wings reduced to 
stumps, may easily be found; the majority are grouped in 
pairs, male and female, each of which may be accompanied by 
a few eggs. These pairs are recently formed, and, if originally 
numerous, are subsequently reduced to one or two (see the 
succeeding section on Habits). 
A pair is established, say, in August, and remains to the 
end of the autumn with only fifteen or twenty eggs; twelve 
months later, at the end, that is, of the following autumn, it 
will be surrounded with fifteen, twenty, or at most thirty 
young of different ages, the most advanced being large soldiers 
with at most fifteen antennal joints, or larve with a similar 
number, all pilose, and with a very slight indication of wings, 
