BUREAU OF ENTOMOLOGY. 413 



five colonies by direct counting of the brood. In order to interfere 

 less with the colony activity, records were made during 1921 by 

 means of photographs of the sealed brood in 16 colonies, and in 1922 

 this was done with 32 colonies. The work during 1923 is on 8 

 colonies only, to clear up certain points not fully explained by the 

 previous data. A manuscript has been submitted for publication 

 giving a summary of the results of the work for the first two years, 

 and two papers have been prepared for publication outside the de- 

 partment in which certain points in this investigation are discussed. 



During the latter part of the season of 1922, observations were 

 made on the feeding and care of honeybee larvse during the various 

 periods of their larval development. It is found that the food given 

 the larva just after hatching is given at one time, in what has been 

 designated mass feeding. After the original food supply is ex- 

 hausted, which occurs at about the end of the second day of larval 

 life, feeding continues as needed by the larva by what has been 

 designated progressive feeding. The change from mass feeding to 

 progressive feeding is doubtless correlated with the change in the 

 composition of the larval food which has long been known to occur, 

 but which was formerly believed to occur much later. A manuscript 

 on this subject has been submitted for publication by the department. 

 The work on the responses of bees to light of various colors and 

 intensities was continued through the active season of 1922 and has 

 been renewed during the present season. 



The manipulation of wax and wax scales by the bees has also been 

 studied, carrying this work on from the points studied by Casteel 

 several years ago in this laboratory, and the manner in which the wax 

 is handled by the mandibles of the bee when being elaborated into 

 the comb has been determined. 



The work on the flight of bees by the special apparatus devised by 

 A. E. Lundie has been completed and the results incorporated in a 

 manuscript which has been submitted for publication by the depart- 

 ment. A large variation has been found in the flight of bees accord- 

 ing to temperature conditions and also with regard to the honey flows. 



Physiology of bees. — The work mentioned in the last report on 

 the availability of various carbohydrates to bees has been con- 

 tinued, certain additional observations having been advisable because 

 of the publication of a paper by certain foreign observers on the 

 enzymes found in the alimentary tract of the bee, the results of which 

 failed to agree fully with the 'findings in the present investigation. 

 A repetition of the work with certain modifications has failed to 

 change in any way the results reported last year, from which it is 

 concluded that the determination of the enzymes in the alimentary 

 tract alone is not a reliable guide in determining what foods are avail- 

 able to honeybees. A brief summary of the results of this work 

 has been prepared for publication outside the department. 



The work on the changes in the cenocytes according to the age of 

 the worker bee has been continued during the present active season. 

 Wliile certain changes are observed in these peculiar cells during the 

 course of the life of the worker bee, the significance of these changes 

 is not yet wholly clear. , , , . , 



The rate of growth of the honeybee larvae has long been recognized 

 as exceedingly rapid. During the past year a paper by Drs. James 



