414 A2^KUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



A. Nelson and A. P. Sturtevant was submitted for publication, in 

 which the results of careful weighings were recorded at intervals dur- 

 ing the entire period of larval development and during the first part 

 of the period when the developing larva is sealed over. It is found 

 that the larva increases in weight 1,550 times during a period of five 

 and a half days and that during the early part of the larval period 

 the rate of development may reach 621 per cent a day. 



It appears that the number of molts of the developing larva has 

 never been accurately determined. A study of this subject has been 

 undertaken and it has been found that, in spite of the excessive rate 

 of development and the constant increase in size during the feeding 

 period, there are but four molts during larval life, and that con- 

 siderable increase in body size and weight occurs between molts. 



In connection with observations on the behavior and physiology of 

 the bee, constant need is felt for more detailed information on the 

 anatomy of the adult bee. 



The study of the colors of American honeys, begun in cooperation 

 with the Bureau of Agricultural Economics, has been continued dur- 

 ing the present active season. The various samples of honey, 450 in 

 all from all parts of the country, have all been measured for the 

 transmission of lights of various wave lengths by means of the 

 spectrophotometer, and the samples have been arranged according to 

 this transmission of light. There are no natural divisions of honey 

 into colors, so that whatever grades are established must be more or 

 less arbitrary. An effort is now being made to obtain materials which 

 will give proper color values for honey graders. 



The examination of the pollen grains in the honey samples col- 

 lected, which is being clone in the microchemical laboratory of the 

 Bureau of Chemistry, has shown that in all probability this is not a 

 safe way to determine the floral source of honeys, as has been com- 

 monly assumed. 



In 'connection with the study of the colors of honey, it was found 

 that honeys vary greatly in their transparency even though there is 

 no granulation. To determine the cause of the cloudiness, arrange- 

 ments were made during the past fiscal year for a cooperative inves- 

 tigation of the materials in honeys other than the three common 

 sugars, and an expert was appointed for this work, which is being 

 done in the carbohydrate laboratory of the Bureau of Chemistry. 

 Five separate plant-coloring materials have so far been extracted 

 from normal honej^s. Some of the coloring materials are colloidal, 

 which doubtless accounts in part for the cloudy effects observed in 

 some samples. 



Diseases or bees. — ^Work on the distribution of the Isle of Wight 

 disease of bees has been continued through a careful survey of all 

 records available from foreign countries, and a manuscript has been 

 submitted for publication in which are recorded for the use of Ameri- 

 can beekeepers all available data on this subject, together with a 

 statement regarding the steps taken by other countries to control 

 this disease or to prevent its introduction where it is not yet found. 

 The disease is now definitely found throughout the British Isles, in 

 France, and in French Switzerland. Importation of bees has been 

 restricted in Switzerland, the Union of South Africa, Australia, 

 and the Dominion of Canada, as well as in certain other countries, 



