XV 



Duration and Rate of Development 



Early in the course of the present work, efforts were made to 

 determine the rate of development, that is, the length of time 

 required by the egg to reach a particular stage. Unexpected 

 difficulties were encountered, and the problem was found much 

 less easy of successful solution than was at first anticipated. This 

 was doubtless due to ignorance of the proper method, and much 

 time was consumed in unsuccessful experimentation. In general 

 two methods were tried. The first is a modification of those 

 employed by Petrunkewitsch (1902) and Dickel (1904). It con- 

 sists in removing a frame from the brood nest of a vigorous 

 colony, and replacing it by an empty frame, upon which the queen 

 is placed. The hive is then closed for a period of two or three 

 hours. The experiment was varied by using two or more empty 

 frames, examining them every two hours. This method, after 

 many trials, was abandoned, since it was seldom successful. The 

 failure of this series of experiments was probably due in part, at 

 least, to the fact that they were undertaken too late in the season, 

 after the main honey flow had ceased. Continued attempts how- 

 ever were made to remedy this unfavorable condition by feeding 

 thin sugar syrup by means of a "pepper box" feeder placed above 

 the frames. Next a single frame observation hive was used, the 

 queen being watched continuously in the hope that some time dur- 

 ing the day the queen would deposit during a two-hour period a 

 number of eggs sufficient for the purpose in hand. This ex- 

 periment was a total failure since not once during the several days 

 she was under observation did she deposit more than a few eggs, 

 and these at long and infrequent intervals, practically all of the 

 eggs being laid during the night. It may be added that the ob- 

 servation hive was kept in a warm but shaded position out of 

 doors, in one of the large breeding cages used by the entomolo- 

 gists of the Department. The third set of experiments was mod- 

 erately successful. The method used in these was the following : 



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