24 



BULLETIN 1339, U. S. DEPARTMENT OF AGRICULTURE 



a'^few hours at the close of the day for the accumulation of net 

 gain. 



'J^On September 25, 1922, colony B sustained the maximum morn- 

 ing loss of the season (fig. 9). The energy expended by the bees 

 on this day, from the beekeeper's point of view, was misappropriated 

 since the result of the day's labor netted the colony a loss of 255 

 grams. The weather of this day was ideal in every respect, and the 

 bees evidently searched for nectar but found little or none. The 

 average morning loss of the spring period is insignificant in com- 

 parison with that of the fall period. Figure 9 illustrates the mag- 

 nitude of the morning losses on September 23 and 25, 1922, 

 respectively, while Figure 10 shows the average loss for the entire 

 fall honey flow of that year. 



^ *st 



Fig 10. — Graphs of average hourly changes in weight, temperature, relative humidity, and total hours of 



sunshine. Colony B, fall period 



MIDDAY DECLINE IN RATE OF GAIN 



Although it is possible to distinguish the midday decline in rate 

 of gain in weight during the majority of the fall days, it is seldom 

 pronounced in its character. It is shown in the shaded portion of 

 Figure 10, which presents the average variations in weight for each 

 hour of the day in the fall period. The graphs of actual weights of 

 fall days do not show this midday decline because it occurs so 

 shortly after the time when the colony stops losing weight. The 

 effect of the midday decline, as determined by bridging the gap at 

 this period upon the net gain, is, however, greater than it is during 

 the spring, since in this case the net gain was decreased 50.66 per 

 cent on account of it. 



