THE FLIGHT ACTIVITIES OF THE HONEYBEE 37 



are balanced by almost equal incoming numbers. Under these con- 

 ditions it was found that the number of bees in the field remained 

 nearly constant. 



Under honey-flow conditions the main flight to the field usually 

 occurred some three to four hours earlier than in the dearth. 



From the graphs representing the progressive totals of outgoing 

 and incoming bees the average duration of each flight at any period 

 of the day can readily be determined. During the main flight for 

 the day, when usually a balanced condition of flight is maintained, 

 these graphs are represented bj two almost parallel straight lines. 

 The morning and evening flights are very much shorter than those 

 that take place in the main period of the day's flight, a variation of 

 as much as from 15 minutes to 1 hour and 43 minutes occurring in 

 one day. Taking all the days for which the average duration of the 

 trips was determined, it is found that this duration varies from 8 

 minutes to as much as 1 hour and 54 minutes. In the honey flow 

 the trips are much shorter than they are in a dearth. 



Although the colony was not manipulated periodically so as to 

 take a census of the field bees, the figures available seem to show 

 that even in a heavy honey flow the bees spend more time in the 

 hive between trips than they do on the trip itself. 



By knowing the amount of nectar gathered on any day and the 

 total number of bees which return, the minimum weight of the aver- 

 age load carried by each bee can be estimated. The highest mini- 

 mum average load obtained was on May 22, when 44,597 bees aver- 

 aged 25.3 milligrams each. Although there is a close relation be- 

 tween the amount of nectar gathered on any day and the amount 

 of nectar available to the bees, this relation is not absolute. The 

 average load per bee is the true indicant of the available nectar. 



Assuming that the errors on the outgoing and incoming gates bal- 

 anced each other, the records for 89 days show that of the 2,434,666 

 bees which left the hive 3.16 per cent did not return. This would 

 mean that on an average a bee makes about 31.65 trips before death 

 overtakes it. 



Of the 65,178 bees lost from all causes 1.63 per cent died in the 

 hive. 



Except for certain difficulties which were eventually over- 

 come, at no time during the three and one-half months of this in- 

 vestigation did these instruments produce any discernible abnormal- 

 ity in the general behavior of the colony. The highest rate at which 

 the gates were ever worked was during a quarter of an hour preced- 

 ing a storm, when each incoming gate admitted in these 15 consecu- 

 tive minutes an average of 14 bees per minute. 



