2 BULLETIN" 1328, U. S. DEPARTMENT OF AGRICULTURE 



While reading an interesting paper* by Leon Dufour, 2 in which 

 are shown the great variations which the weight of a hive under- 

 goes in the course of a single day, the writer, seeing how the in- 

 coming nectar and pollen modified the interpretations of the 

 flights which occurred, realized more fully the scientific value of an 

 automatic apparatus which would register the exits and returns of 

 the individual bees, and was led to spend the greater part of the 

 winter of 1921-22 in devising an apparatus for this purpose. 



Actual recording of individual flights was begun on April 8, 1922, 

 with 14 units of the apparatus in place. On May 10 the full quota 

 of 30 instruments was installed and readings were continued regu- 

 larly, including Sundays and holidays, from daylight to dark, until 

 July 29, except for six days, when the work was interrupted by 

 certain necessary modifications or adjustments of the apparatus. 

 During this period some five million flights to and from the hive 

 were recorded, the gross weight of the bees representing half a ton. 



Since the first object of this experiment was to determine the prac- 

 ticability of obtaining data on problems pertaining to the flight of 

 bees by means of an automatic recording mechanism, rather than to 

 make a study of any one of these problems, and since there appears 

 to be no immediate opportunity for the writer to continue this in- 

 teresting line of investigation, it seems best to record the data so 

 far obtained, that they may serve as at least an introduction to a 

 further study of this phase of bee behavior. 



THE APPARATUS 



At the outset it was clear that, on account of the limited space at 

 the hive entrance, the most practical apparatus for counting the 

 flights of bees would be one in which each bee would establish elec- 

 trical contact as it left or as it entered the hive. Any such appa- 

 ratus must consist of as many units as will accommodate the full 

 flight of the colony under experimentation, each unit consisting of 

 one contact device and one recording mechanism. 



THE CONTACT DEVICE 



A device for establishing electrical contact's that will give the de- 

 sired data is one which requires for its operation little or no exertion 

 on the part of the bee and which will delay the bee very little or 

 not at all in its departure or return. To meet these requirements 

 there are at least three possible methods of approach, arranged here 

 in the ascending order of their complexity and expense. 



(1) To allow the bee to push against some mechanism. 



(2) To allow the weight of the bee to operate some mechanism. 



(3) To use a minute electric current, the circuit of which is closed 

 by the body of the bee itself as it passes the terminals, but not strong 

 enough to cause any modification of behavior, and then to amplify 

 this current SO' as to operate the recording mechanism. 



Working on the plan of allowing the bee to push against some 

 mechanism, a modification of the ordinary bee-escape which allows 

 bees to pass but one way was tried. A small wire was soldered at 



2 Dufour, Lgon. Travail des butineuses et r6colte du miel. In L'Apiculteur, vol. 41, no. 

 8, pp. 300-312. 1897. 



