UNITED STATES DEPARTMENT OF AGRICULTURE 
Contribution from the Bureau of Entomology 
L. O. HOWARD, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
June 12, 1919 
NOSEMA-DISEASE, 
ByG. F. White, 
Specialist in Insect Diseases. 
CONTENTS. 
Page. 
Introduction 1 
Name of disease 3 
Digestive tract of adult bees 4 
Cause of Nosema-disease 7 
A three-year study of Nosema infection in an 
apiary 13 
Symptoms of Nosema-disease 21 
Methods employed in experimental studies . . 22 
Effect of Nosema infection on the colony and 
on the apiary. 23 
Resistance of Nosema apis to heating 29 
Resistance of Nosema apis to drying 31 
Resistance of Nosema apis to fermentation. . . 33 
Page. 
Resistance of Nosema apis to putrefaction ... 35 
Resistance of Nosema apis to direct sunlight . . 37 
Period Nosema apis remains virulent 39 
Infectiousness of brood-combs from Nosema- 
infected colonies 43 
Resistance of Nosema apis to carbolic acid. . . 44 
Effect of drugs on Nosema-disease 44 
Modes of transmission of Nosema-disease 46 
Diagnosis of Nosema-disease 48 
Prognosis in Nosema-disease. 53 
Summary and conclusions 56 
Literature cited 58 
INTRODUCTION. 
Nosema-disease is an infectious disease of adult honeybees. It 
causes the death of many individual bees, tending thereby to weaken 
the colonies infected. Many colonies die of the disease, but the per- 
centage of deaths is comparatively small and entire apiaries are 
rarely, if ever, destroyed by it. It is not to be considered, therefore, 
as a particularly serious disorder. This is shown by the results 
recorded throughout the present paper. It is to be thought of rather 
as a disease the losses from which are less to the infected apiary than 
the losses from either of the foulbroods, although greater than those 
103789°— 19— Bull. 780 1 
