12 BULLETIX 1319, U. S. DEPARTMENT OF AGRICULTURE 
DESCRIPTION OF THE COLONIES USED IN 1921 
The brood-rearing investigation in 1921, as originally planned, 
was to be carried out along lines which would tend to show the effects 
of insulation, of stores, and of the age of the queen. Accordingly, 
each of the 16 colonies used in 1921 had been wintered in two 10-frame 
Langstroth hive bodies, eight colonies having been left all winter 
without packing and eight having been wintered in quadruple 
packing cases. The colonies were not in any way manipulated 
for the purpose of changing their brood-rearing rate, except that 
the addition of frames or supers had some influence in this respect. 
The record is, therefore, largely a presentation of what bees do 
without the interference of the beekeeper. The colonies without 
packing comprised two groups of four, and it was the original in- 
tention that the packed colonies should comprise the colonies in 
two packing cases. Since, however, one of the packed colonies 
became queenless during the winter, a colony packed in another 
group was used in its place. The group containing three colonies 
was unpacked on March 8, while the substituted colony (No. 10) 
was unpacked on March 21; but the group containing four colonies 
was not unpacked until May 5. Three of the colonies without 
packing had queens bred in 1919, whereas all the others, including 
both those with and without packing, had 1920 queens. Lack of 
stores was not during 1921 a factor in the brood-rearing activity of 
the eight unprotected colonies, as each colony proved to have more 
than sufficient stores for all purposes. Of the colonies packed all 
winter, four had heavy stores of honey, whereas the other four had 
light stores, all in the second hive body. The early spring was so 
favorable for incoming nectar and pollen, however, that each colony 
except No. 15 had sufficient stores for spring brood-rearing purposes. 
All the 16 colonies used were located at the Bee Culture Laboratory, 
Bureau of Entomology, at Somerset, Md., near Washington, D. C. 
In an endeavor to determine some of the factors which influence 
brood-rearing activity during the three phases of the active season, 
it* is of interest to study the seasonal brood records of these 16 indi- 
vidual colonies. For this purpose the general features of the brood- 
rearing activity in 1921 of 15 colonies are presented here, as well as a 
somewhat more detailed study of the brood record of an additional 
colony for two successive seasons. For each of these colonies a 
seasonal curve (figs. 1 to 16) has been constructed, based on counts 
(Tables 1 to 16) of sealed brood made from photographic records 
taken in 1921, as well as an additional curve (fig. 17) for one of these 
colonies, based on data (Table 17) from 1922. Although at first 
glance the 17 curves seem to show little correlation, they reveal 
definite relationships on closer study. The apparent differences 
result from abnormal conditions within individual colonies, which 
caused modifications in the brood-rearing responses. On the whole, 
the 17 curves point to certain more or less definite and constant 
seasonal variations in brood-rearing activity, due to normal, seasonal 
stimuli, but subject to modifications by the presence of any abnormal 
factors. This fact becomes apparent upon an examination of the 
two successive seasonal curves presentee! for colony Xo. 4. 
It may be noted in passing that, even before unpacking colonies 
wintered in two hive bodies in quadruple packing cases, removal of 
frames from the lower hive bodies can be accomplished readily by 
