12 Farmers’ Bulletin 1198. 
food is available, the amount of brood is usually increased until a 
certain maximum is reached, after which brood-rearing declines. 
When spring brood-rearing is most extensive the queen may lay more 
than 3,000 eggs daily, but she does this during a short time only. 
There is, therefore, a well-marked period of extensive brood-rearing 
in the spring. Apparently this spring expansion of brood-rearing is 
stimulated by the oncoming of spring following the period of little 
or no brood-rearing. It is stimulated also by early incoming pollen 
and nectar, but may occur even when these are lacking, provided a 
sufficient quantity of honey and pollen is stored in the hives and 
water is available. In this respect the spring period of extensive 
brood-rearing differs greatly from other periods of more or less ex- 
tensive brood-rearing, since after the first great expansion in brood- 
rearing the presence of honey stored in the hive is not a sufficient 
stimulus to cause the bees to rear brood extensively. 
In all regions swarming may be expected within a well-defined 
“swarming season ” which coincides roughly with the period of maxi- 
mum brood-rearing. When there is a well-marked secondary ex- 
pansion in brood-rearing later in the season it may be accompanied 
by a secondary swarming season. When the primary period of maxi- 
mum brood-rearing is prevented because of extreme weakness of the 
colony, or a dearth of food, swarming may simply be postponed until 
a later honey-flow and may then be expected as during the normal 
swarming season. If no period of extensive broad-rearing takes place 
during the season there is usually no swarming. Differences in sea- 
sons and differences in localities may modify the rapidity with which 
brood-rearing is carried on, so that the maximum amount of brood 
may be greater in certain years than in others and greater in certain 
localities than in others. 
Other things being equal, the tendency to swarm is the greatest in 
those localities in which, on account of climatic conditions and avail- 
able food, the bees increase brood-rearing most rapidly in the spring. 
In any locality the tendency to swarm is greatest during those years 
when, because of favorable conditions, the bees build up in the short- 
est interval in the spring. Among the colonies in the apiary the 
tendency to swarm is greatest in those colonies which reach their 
peak of brood-rearing most rapidly. When colonies of bees build up 
so rapidly in the spring that a maximum of 60,000 to 70,000 cells of 
brood is reached, they have during a certain period a large propor- 
tion of recently emerged and emerging bees. Such colonies are in 
the best possible condition to gather and store a crop of honey if 
the honey-flow begins at about the time they reach their maximum in 
brood-rearing, but they are strongly inclined to swarm. 
When brood-rearing is conducted moderately, colonies may have 
as many workers when they reach their maximum strength, but they . 
