326 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



in an effort to explain the phenomena of dysentery (spotting of 

 feces) so frequently observed when bees are not wintering well. At 

 that time it was learned that bees are unable to digest certain carbo- 

 hydrates Avhich are found in inferior grades of honey and in honey- 

 dew honey, and these results were incorporated in publications on win- 

 tering. The subject required additional experimentation before defi- 

 nite statements could be made concerning certain interesting carbo- 

 hydrates, and during the spring of 1922 additional feeding experi- 

 ments were undertaken. A large series of chemically pure carbohy- 

 drates were obtained and fed to bees to determine their availability as 

 food. Most of the materials chosen were those which bees might 

 obtain in the gathering of nectar in the flowers. It is now evident 

 that the ability of bees to digest carbohydrates is exceedingly limited. 

 The results obtained explain fully the cause of dysentery in winter 

 and emphasize the need of great care in the choice of winter stores. 

 When bees are free to fly during the summer any of these materials 

 which they can not digest will be eliminated through the feces ; but 

 during confinement to the hive this is impossible, and the condition 

 known as dysentery results, often followed by the death of the entire 

 colony. Methods for the prevention of this condition have been 

 incorporated in publications of the department dealing with winter- 

 ing of bees. 



Tests have been made of the insulating value of various commer- 

 cial double-walled hives on the American market to determine their 

 suitability for wintering. The results of this work have been pre- 

 sented for publication as a circular of the department. 



The results of the experiments on wintering bees have been further 

 worked up. There still remains considerable Avork to be done before 

 the full results of the experiments on wintering bees are available 

 for publication, but we hope to submit them in a few months. 



The work on the factors influencing the ae^ing of bees which was 

 mentioned in the last report was discontinued at the close of the sum- 

 mer of 1921, l)ut was again undertaken in the spring of 1922. For 

 the present, attention is being given especially to the changes which 

 occur in the oenocytes in the adult worker bee. The purpose of this 

 work is to determine the changes which occur in bees when they wear 

 themselves out by excessive activity, especially during the winter 

 months, when they are confined to the hive, and it is hoped that when 

 these phenomena are understood, remedies for the great losses caused 

 by the death of the worn-out bees may be devised. 



As was stated in the previous report, some samples of supposedly 

 poisonous honeys were obtained and sul)mitted to chemical analysis. 

 This work failed to show the cause of the trouble, and during the 

 spring of 1922 an effort was made to determine the plant which fur- 

 nishecl this honey. In cooperation with the Bureau of Plant Indus- 

 try, it has been found to be the mountain laurel. It still remains 

 necessary by chemical analysis to determine the presence of the poi- 

 sonous material in the honey. It is of the greatest importance also 

 that a study be made to determine under what conditions this plant 

 secretes ne(?tar which is poisonous, for it seems evident that it does 

 not always do so. since the plant has a wide distribution and poison- 

 ous honey is not commonly produced. The chemical work on this 

 lioney will be undertaken as soon as possible. 



