April, '22] PARK: BEES, TIME AND LABOR FACTORS 133 



Field trips by pollen bearers were found to be considerably shorter 

 as a rule than those made by nectar carriers. As shown in Fig. 5, A, 

 almost 40 percent of the field trip records for 1920 fell within the 6-10 

 minute class, and 97.5 percent were completed in 30 minutes or less. 

 None of the 1921 records for field trips fell within the 2-6 minute class, 

 and only 20 percent fell within the 6-10 minute class, yet 99 percent 

 were accomplished in 30 m.inutes or less. The modal time, however, 

 was 15.5 minutes as against only 8.6 minutes in 1920. 



The curves for hive stays appear in Fig. 5, B, and are very similar for 

 the two seasons. The peaks both fell within the 2-4 minute class. In 

 1920, this class received 38 percent of the records as against 36 percent 

 in 1921, but the percentage of hive stays that occupied 15 minutes or 

 less was 98 in 1921 as against 88 in 1920. The most frequent interval 

 spent in the hive between trips was 3.4 minutes in 1920 and 3.7 minutes 

 in 1921. 



In Fig. 5, C, we have the curves for round trips. The modal interval 

 for the 1920 records was 12.6 minutes but was 16.5 minutes in 1921. 

 The percentages of records falling within the modal class were nearly 

 the same in both cases. In fact, the two curves are much alike as to 

 area and shape, but the one for 1921 stands about 4 minutes farther to 

 the right than does the other. This indicates in a general way that the 

 bees that gathered com pollen during the period of observation in 1921 

 consumed about 4 minutes per trip more than did those in 1920 when corn 

 pollen was more plentiful. 



The maximum nimiber of trips recorded in one day for a bee gathering 

 pollen from com was 20 in 1920 but only 11 in 1921 while the averages 

 were about 8 and 5>2, respectively. As a rule, com pollen was not 

 available in the afternoon so these figures represented only about half 

 a day in actual working time. 



Labor Factors 



Before the nectar carrying capacity of the honeybee could be found, 

 it was necessary to determine the minimum flying weight. This determ- 

 ination was. made by three different methods, all of which gave approxi- 

 m.ately 82 mg. as the average minimum flying weight for Italian bees. 

 The load carried was determined by deducting this factor from the gross 

 weight of the loaded bee. The maximum nectar carrying capacity was 

 found to be approximately 70 mg. or about 85 percent of the weight of 

 the bee itself. Average loads were found to weigh 40 mg. or about 

 50 percent of the weight of the bee. 



The weight of pollen loads carried by bees apparently differs according 

 to the source, ranging from 12 and 14 mg. for elm and com, respectively, 



