34 BULLETIN 1328, U. S. DEPARTMENT OF AGRICULTURE 



The records for 89 days, which have been chosen as representative 

 of the data obtained, show that of the bees which left the hive (2,434,- 

 666), 3.16 per cent did not return. If the assumption is made that 

 the errors in the counts of exits and entrances balance each other, 

 this would mean, since every exit represents a trip by a bee, that one 

 bee dies after every 31.65 exits have occurred, or that each bee makes 

 31.65 trips before death overtakes it in the field. 



It is generally accepted that the mortality of honeybees is in pro- 

 portion to the amount of work which they do. It is also evident that 

 during the night, when flights do not occur, all deaths will take place 

 within the hive, and during the active season there is usually a period 

 of 10 hours daily when there are no flights. If, therefore, about 98 

 per cent of the deaths from the colony occur in the field, this indicates 

 that most of the deaths occur during the approximately 14 hours of 

 flight. These data suggest that the energy expended by the bees 

 in flight and in activities outside the hive greatly exceeds that ex- 

 pended within the hive. This conclusion is to be anticipated from 

 the enormous amount of energy which must be expended in flight. 

 Assuming (1) that a field bee is away from the hive one-half of the 

 flying hours, (2) that a death rate of 2 per cent occurs within the 

 hive, and (3) that there is a 14-hour period of flight for the day, 

 the chance of a bee dying outside the hive during any given hour 

 of the period of flight is about 120 times as great as the chance that 

 death shall occur within the hive. This at least suggests that for 

 any given instant the expenditure of energy on flight or away from 

 the hive is about 120 times as great as that expended by a single 

 bee within the hive. 



THE BEHAVIOR OF THE BEES TO THE INSTRUMENTS 



In the initial stages of the experiment, although about 2,000 bees 

 passed satisfactorily through the experimental model, the reaction 

 of the colony as a whole to the complete set of instruments was en- 

 tirely problematical. The success or failure of the experiment, 

 therefore, depended upon this reaction. The plan of placing the 

 outgoing gates above the incoming ones, so that the actual entrance 

 apertures were only about 2 inches below the exit apertures, proved 

 very satisfactory, only an occasional bee attempting to enter the hive 

 by an outgoing gate. 



Considering the tunnel of the contact device as a hole in the wall 

 of the hive which drops a distance equal to twice the height of a 

 bee while the latter passes through it, the delay produced by these 

 instruments is negligible and the only abnormality introduced is the 

 jar of the tunnel meeting the lower stop. Owing to the fact that 

 any hesitancy of a bee in walking out of the tunnel prevents another 

 from using this aperture, a net delay on all the apertures ensues. 

 The return movement of the tunnel to receive the next bee is a minor 

 source of delay when compared with that produced by the hesitancy 

 shown by some of the bees in selecting the aperture by which they 

 finally enter. Probably this hesitancy on the outgoing gates is not 

 so marked. It has been impossible to determine the actual delay 

 produced. On seeing the rapidity shown on certain occasions by 

 some of the bees when leaving the outgoing gates, one would not 

 hesitate to state that these bees left the hive as rapidly as they do 



