WEATHER AND CHANGE IN WEIGHT OP BEE COLONY 9 



nocturnal loss due to evaporation and consumption for colony main- 

 tenance. Eis, of course, located on the time scale 24 hours after A, and 

 becomes the starting point (^4) for the following day. The only 

 two points which are fixed with regard to time are therefore A and E. 

 In all diagrams except Figure 2 the base line is drawn, not from the 

 point denoting the weight at the starting point (A), but from a zero 

 point raised by an amount equal to the loss in weight between 4 and 

 5 (or, in the fall, 5 and 6) o' lock. This is done to show more clearly 

 in the graphs the time when loss of weight of the hive actually begins, 

 as the bees begin flying in the morning. Calculations of all data 

 were, however, based on zero at the point A (actual weight a" 5 or 6 

 o'clock). Nowhere in the calculations can allowance be made for 

 consumption for colony maintenance, which remains an unknown 

 factor. Th? gai :s during the day would be more, and the evapora- 

 tion loss at night wmld be less, if this factor could be known. 



The name "midday decline" is given to the decline in the amount 

 ofjgain from hour to hour occurring near midday. Although gains 



+ 



8 



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'& 6 7 S 9 /O // /2' 



sfAS 



2 3 4- S" 6 7 S 9 /O // /g' V g 3 4- £* 



yL r 



3 



Fig. 2.— Division of changes in the weight of a colony of bees 



are actually taking place during this period on most days, there is a 

 noticeable difference in the rate of gain at this time as compared 

 with that of the hours immediately before and after. 



The 24 hours of the day are 'divided into diurnal and nocturnal 

 periods, and the designations a. m. and p. m. are not used, since 

 they have no biological significance. The differentiation of diurnal 

 from nocturnal in this discussion is dependent upon the activity of 

 the bees and not on light or darkness. The diurnal period ends and 

 the nocturnal period commences when the weight of the colony 

 ceases gaining, toward the close of the day, and the diurnal period 

 begins, not necessarily at dawn, but at the hour when bee activity 

 outside the hive becomes noticeable. Obviously, flight in the 

 afternoons may be prevented or reduced by rain or inclement 

 weather; and, to prevent the necessity of discarding data obtained 

 on such days, the point D is located in the calculation of the data 

 for 1922 at the time when bees cease gaining and begin to lose on 

 the days immediately preceding and following the days in question, 



42201—25 2 



