132 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 15 



In 1921, about 21 percent of the recorded round trips belonged in the 

 41-50 minute class. Scarcely 50 percent fell between 20 and 50 minutes 

 and only 80 percent were completed in less than 1)4 hours. The mean 

 time was 63 minutes but the modal time was 46 minutes. 



The maximum number of trips recorded in one day for a nectar carrier 

 was 24 in 1920 and 17 in 1921. The average number of trips per day 

 was found to be 13>^ in 1920 while in 1921 the average was only 7 per 

 day. If the mean time for round trips for each year be multiplied 

 by the average number of trips per day for the same year, we arrive 

 at an approximation to the average time per day spent in nectar gathering. 

 This gives about 8>^ hours for field work in 1920 and about 7}4 hours 

 for 1921. 



f Pollen Gathering 



Time records for field trips, hive stays and rpund trips by bees gather-, 

 ing pollen from com were secured in 1920 and again in 1921. The 

 weather conditions in both instances were favorable enough fof the 

 production of pollen by the plant and for field work on the part of the 

 bees. But in 1920, the data were taken at times when there was an 

 abundance of com in bloom, whereas, in 1921, the main period of bloom 

 had passed before the records were obtained. We have, then, as for 

 nectar carriers, one set of data secured under favorable conditions, 

 and the other vinder less favorable conditions. The records for the 

 two seasons have been plotted against each other in the form of fre- 

 quency curves which appear in Fig. 5, A. B and C. In every case the 

 curve is a decided skew, so for purposes of comparison^ the mode is used 

 in preference to the mean. 



TTlinutes 



11 zo 



itti 



Fig, 5. Showing the frequency distribution of time records made by pollen bearers 

 ■when gathering pollen from com under favorable and unfavorable conditions. A, 

 Pield trip records. B, Hive stay records. C, Round trip records. 



