UNITED STATES DEPARTMENT OF AGRICULTURE 



m BULLETIN No. 809 



*?Kmk*^<l§£y Contribution from the Bureau of Entomoloev •! 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



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Washington, D. C. 



PROFESSIONAL PAPER 



March 10, 1920 



AMERICAN FOULBROOD 



By G. F. White 

 Specialist in Insect Diseases 



CONTENTS 



Introduction 1 



Name of the disease 2 



Healthy brood at the age at which it dies of 



American foulbrood 3 



Symptoms 5 



Etiology 11 



Technique 17 



Thermal death point of American foulbrood 



spores 22 



Resistance of American foulbrood spores to 



drying 29 



Resistance of American foulbrood spores to 



direct sunlight 29 



Resistance of American foulbrood spores to 



fermentation 31 



Resistance of American foulbrood spores to 



chemical disinfectants 31 



Effect of drugs on American foulbrood 32 



Modes of transmission 34 



Diagnosis 36 



Prognosis 38 



Summary and conclusions 39 



Literature cited 42 



Explanation of plates 45 



INTRODUCTION 



American foulbrood is an infectious disease of the brood of bees 

 caused by Bacillus larvae. The disease is characterized by a decided 

 ropiness of the decaying brood and a peculiar foul odor. It is very 

 widely distributed, is readily recognized, and is of much economic 

 importance. Its existence has been known for a long time, and bee- 

 keepers have established many facts concerning it through observa- 

 tions made while practicing their profession. While there is a con- 

 sensus of opinion among beekeepers on certain points regarding the 

 disorder, there are others on which a diversity of views has existed 

 and still others about which almost nothing of a definite nature has 

 been known. 



Former work was- directed primarily toward the determination of 

 the cause of the disease. Among the problems considered in the 

 present studies are: The resistance of Bacillus larvae to heat, drying, 

 sunlight, fermentation, and disinfectants; the effect of the disease on 

 the colony and on the apiary; and the transmission, diagnosis, and 

 prognosis of the disease. Direct studies on the treatment of the 



132862°— 19— Bull. 809 1 



