1919 



AMERICAN BEE JOURNAL 



225 



is poized. By gentle traction the di- 

 gestive tract forward to and includ- 

 ing the stomach, and occasionally 

 also, the proventriculus and honey 

 sac. may be removed (rig. 2). The 

 largest and usually the last portion 

 to rome away by this method is the 

 stomach (ventriculus). This is a rela- 

 tive'j thick-walled, elongated and 

 m'or< O! less spindle-shaped organ. 



Tht color and size of healthy stom- 

 ach' are variable. They vary some- 

 what with the age of the bee an 1 rilso 

 wi'h the season of the year. The 

 color of the stomach of workers 

 ranges from a light yellowish brown 

 to a deep red, corresponding to the 

 flesh of the ox. Sometimes the ap- 

 pearance of the organ is due, in part, 

 to the presence of pollen in it. The 

 stomach of the drone is smaller and 

 lighter in color than that of the 

 worker. The stomach of the queen 

 is also smaller than that of the 

 worker, but less difference exists, in 

 her case, than in the case of the 

 drone. 



The diseased stomach is lighter in 

 color than the healthy one. Late in 

 the course of the disease it is white. 

 The diseased organ not infrequently 

 tears by the traction which is neces- 

 sary to its removal and is more eas- 

 ily crushed than the healthy one, and 

 when crushed the mass is milky in 

 appearance. 

 Nosema-disease Weakens Colonies 



Since the stomach of a bee (figs. 2, 

 3, 4, 5 and 6) is very abnormal in No- 

 sema-disease, it is only natural to ex- 

 pect that an affected bee is less effi- 

 cient as a member of the colony than 

 a health}- one. The results obtained 

 from experiments support this posi- 

 tion. It was found that the strength 

 of experimental colonies diminished 

 as a result of Xosema infection, when 

 no brood, or very little of it, was be- 

 ing reared. Furthermore, it was 

 found that by inoculating a colony 

 every 3 or 4 weeks during the more 

 active brood-rearing season, the 

 strength of the colony remains more 

 or less uniform, while colonies in the 

 same apiary which have not been in- 

 oculated make the customary gain. 



Ten colonies, each of which were 

 easily accommodated i n from 6 to 7 

 brood-frames, were inoculated about 

 the middle of September, 1912. These 

 weakened as a result of the infection 

 that was produced. By the middle of 



Fig. 7. — Apiary 



vhich the 1915 experiments 



May of the following spring, 5 of 

 them were dead. The 5 that lived 

 through the winter, though weak in 

 the spring, recovered from the infec- 

 tion, gained in strength during the 

 brood season, and by autumn were 



as strong as the average for the 

 apiary. Colonies inoculated at the 

 beginning of the active brood-rearing 

 season first lose, but later gain in 

 strength, due to the young bees that 

 are produced. Such colonies, how- 



Fig. 6. — Drawing of section of the wall of diseased stomach. The cells lining the stom- 

 ach which secrete digestive juices and probably also absorb some food substances, are 

 filled with the germs. (Proc. Ent. Soc. Wash. 1918.) 



ever, are not as strong relatively as 

 the uninoculated ones. It is seen, 

 therefore, that Nosema-disease does 

 tend to weaken colonies. 



Nosema-disease Sometimes Kills 

 Colonies 



From what has just been said it 

 might be expected that Nosema-dis- 

 ease. under certain circumstances, 

 may kill colonies. Those which were 

 inoculated in the fall of the year, af- 

 ter the brood-rearing season was 

 over, invariably died somewhat later 

 during the winter. 



Xot only was the disease studied in 

 colonies in which it had been pro- 

 duced by experimental inoculation, 

 but also in an apiary in which it was 

 contracted through natural means. 

 Such an apiary, located near Wash- 

 ington, D. C, furnished a favorable 

 opportunity for a 3-year observation 

 of the disorder as it occurs in nature. 

 The April count of the apiary in 1912 

 u as 24 colonies. 



Of these, 5 died during the bee sea- 

 son and were dead by the end of May. 

 The percentage of Nosema-infected 

 bees, among the field bees of these 

 colonies, ranged from 50 to 100 per 

 cent. Results similar to these were 

 obtained during the remaining two 

 and one-half summers that the studies 

 were being made on the apiary. The 

 facts determined show that Nosema- 

 disease may, and sometimes does, 

 kill colonies. 



Colonies Have a Tendency to Re- 

 cover From Nosema-disease 



In order to maintain Nosema infec- 

 tion, in an experimental colon}-, dur- 

 ing the more active bee season, re- 

 peated inoculations were necessary. 

 In about 2 weeks after an inoculation 

 feeding, practically all field bees are 

 diseased, but after 1 month very few 

 infected ones are present. The dis- 

 eased bees die, the young ones emerg- 

 ing are healthy, the infection spreads 

 very little, if any, from the sick bees 

 to the healthy ones, and as a result 

 the colony is comparatively free from 

 infection. It was seen from the ex- 

 periment referred to above, that 5 

 out of the 10 colonies inoculated in 

 September wintered, and by the fol- 



