30 



BULLETIN 1339, U. S. DEPARTMENT OF AGRICULTURE 



appears evident that either the honey flora in the vicinity of Somer- 

 set, Md., does not respond during the spring period as did the plants 

 studied by Bonnier and Kenoyer, or else that the temperature has 

 such a pronounced effect upon the behavior of the bees that the effect 

 upon nectar secretion is largely obscured. Hot, dry weather often 

 occurs at periods when no nectar is being brought to the hive; at 

 the hottest times, however, it is not at all uncommon for bees to 

 gather large quantities of honeydew of insect origin. Since the bee 

 is a cold-blooded animal it is but natural to expect increased activity 

 with increasing external temperature. 



Table 3 lists the coefficients of correlation between net gain and 

 the various weather factors of the previous day. It will be seen that 

 the coefficient of correlation between the net gain and the average 

 temperature for the entire spring period is .1783 ±.1059. This in- 

 fluence is positive but not otherwise especially significant, since the 

 probable error is high. The correlation of net gain with average 

 nocturnal temperature just preceding the gain is slightly higher, being 

 .2151 ±.1043. Evidently, according to the data presented, tempera- 

 tures of the day on which gains are made have a more direct influence 

 on colony gains than do those of the previous day or night. 



Table 3. — Coefficients of correlation between net gain in colony weight and various 

 weather factors of the preceding day, with their mean and standard deviations for 

 the spring period 



Net gain. 



Diurnal 



average 

 temper- 

 ature 



0. 1783 

 ±. 1059 



Diurnal 

 varia- 

 tion in 

 temper- 

 ature 



0. 3317 

 ±. 0973 



Diurnal 

 av erage 

 relative 

 humid- 

 ity 



Diurnal 

 varia- 

 tion in 

 relative 

 humid- 

 ity 



0. 0329 

 ±. 1093 



0. 0289 

 ±. 1093 



Hours 

 sun- 

 shine 



0. 0246 

 ±. 1093 



Solar 

 radia- 

 tion 



Noc- 

 turnal 

 average 

 temper- 

 ature 



-0. 0804 

 ±. 1087 



0.2151 

 ±. 1043 



Noc- 

 turnal 

 varia- 

 tion in 

 temper- 

 ature 



0. 2472 

 ±. 1027 



Noc- 

 turnal 

 average 

 relative 

 humid- 

 ity 



0. 0005 

 ±. 1094 



Noc- 

 turnal 

 varia- 

 tion in 

 relative 

 humid- 

 ity 



0. 0721 

 ±. 1088 



Mean deviation 



Standard deviation. 



4. 5261 

 2. 4895 



4. 9735 

 2. 3113 



3. 1578 

 2. 3230 



4. 6577 

 2. 4526 



5. 8682 

 2. 7067 



2. 4146 



5. 3682 

 2. 8603 



4. 6577 

 1. 8416 



5. 6840 

 2. 0148 



4-1314 

 2. 3304 



The data taken during the fall period give a correlation coefficient 

 of —.2310 ±.1185 between the average diurnal temperature and the 

 change in weight. This figure is radically different from the corre- 

 lation of .7529 existing between the average diurnal temperature and 

 the net gain for the spring period. The probable error of the fall 

 correlation is large, and this figure is therefore important chiefly 

 because there is a negative correlation. This difference may be due 

 in part to the fact that during the fall the activity of the colony in 

 brood production is carried on under somewhat adverse conditions; 

 that is, the effort necessary properly to care for the brood during the 

 fall is proportionally greater than it is during the spring, and for this 

 reason the bees will go to the fields under conditions otherwise not 

 ideal. In such a case it may be that temperature has a more pro- 

 nounced effect upon nectar secretion than upon bee behavior, and 

 thus results in a negative correlation between average diurnal temper- 

 ature and changes in colony weight. There seems little doubt but 

 that a much greater effort is necessary on the part of the bees during 

 the fall properly to carry on normal colony activity than is needed 

 during the spring. Figure 1 illustrates a day in each of these two 



