VOL. LIX— NO. 7 



HAMILTON, ILL., JULY, 1919 



MONTHLY, $1.00 A YFAR 



SOME OBSERVATIONS ON NOSEMA-DISEASE 



By G. F. While, Bureau of Entomology, Washington, D. C. 



NOSEMA-DISEASE, in many 

 ways, is one of the most inter- 

 esting of the diseases of adult 

 bees. Doubtless the beekeeper al- 

 ready is quite familiar in a general 

 way with the nature of the disorder 

 since the bee journals have carefully 

 presented the facts concerning the 

 disease as they have been determined. 

 Since 1910 the writer has been mak- 

 ing some studies on the disease, and 

 in the present communication there 

 are discussed briefly some of the 

 more important observations ob- 

 tained which would seem to be of in- 

 terest to all beekeepers. In a bulletin* 

 (No. 780) recently issued by the 

 United States Department of Agri- 

 culture, the writer has given in some 

 detail the results obtained which have 

 a more or less direct connection with 

 the problems with which the practical 

 apiarist is confronted. No direct work 

 on the treatment of the disease was 

 undertaken. In planning the investi- 

 gations, however, the problems se- 

 lected were of such a nature that the 

 results obtained from them could be 

 used by the beekeepers in devising 

 methods for treatment. 

 Nosema-disease Not a New Disorder 

 The disorder now known as No- 

 sema-disease was reported by an Eu- 

 ropean observer as early as 1857. 

 That such a disease of bees exists 

 was afterward almost forgotten until 

 the fact was again brought to the at- 

 tention of beekeepers in 1909. The 

 disease is present at least in Austra- 

 lia. Switzerland, Germany, Denmark, 

 England, Canada and the United, 

 States, and has been reported from 



* Bulletin No. 780 was written pri- 

 marily for beekeepers. Strictly tech- 

 nical discussions were purposely 

 avoided in preparing it. While it 

 contains some semi-technical terms, 

 it is believed these will offer no par- 

 ticular obstacle to a satisfactory un- 

 derstanding of the subject matter 

 presented. 



Brazil, also. Most likely it has a 

 much wider distribution, even, than 

 this. The writer found Nosema infec- 

 tion in bees received from 27 differ- 

 ent States in the United States.* 

 These were from the North, the 

 South, the East and the West. The 

 disease is, therefore, very widely dis- 

 tributed in America and is not a new 



* Bulletin No. 92, U. S. Department 

 of Agriculture, May IS, 1914. 



one to cause losses to apiaries. The 

 information regarding the disease is 

 of recent origin, but not the disease 

 itself. It is better to think of the dis- 

 order as one which has been collect- 

 ing toll from apiaries longer than 

 bees have been kept in America, and 

 Dfobably longer than bees have been 

 kept anywhere by man. 



Germ Causing Nosema-disease 



The germ that causes Nosema- 

 disease is a protozoan, a one-celled 

 animal parasite. Nosema apis is the 

 name which has been given to it. The 

 parasite has a growing (vegetation) 

 form and a spore (resting) form. To 

 the apiarist the spore form is the 

 more important. The spores are 

 small oval bodies (fig 1) which, if 

 placed end to end would require 5,000 

 to measure an inch, and if placed 

 side by side would require 10,000 to 

 measure this distance. These spores 

 are taken into the stomach (fig. 2) by 

 the adult bee, with the food or water. 

 The digestive juices acting on the 

 covering of the spore release the 

 young parasite. These young forms 

 immediately find their way to the 

 wall (fig. 3) of the stomach and in- 

 vade it. Once within the wall of the 

 organ they grow rapidly and multi- 

 ply to an enormous extent (figs. 3, 4, 

 5 and 6). Spores are then produced 

 in large numbers and are shed into 

 the stomach and, being mixed with 

 the partially digested food (fig. 3), 

 are carried through the remainder of 

 the intestinal tract, to be voided with 

 the excrement. Should such excre- 

 ment reach the food or water supply 

 of bees it will be seen how other bees 

 might thus become diseased.. 

 Name of the Disease 



Since Nosema-disease has affected 

 apiaries as much in the past as at 

 present, it is of interest to know the 

 name used, by beekeepers, for the 

 condition to which the losses due to 

 it are attributed. Early during the 

 writer's studies, it was observed that 

 the highest percentage of Nosema- 

 infected bees were present in weak 



