20 BULLETIN 780, U. S. DEPAKTMENT OF AGBICtTLTTJKB. 



Table Y.— Summary of results frrnn a study of Nosema infeOion in an apiary. 



Year. 



March. 



April. 



Ifoy. 



June. 



July. 



1912. 

 1913. 

 1914. 

 1915. 



Total. 



410 



60 



1,050 



200 



130 

 220 

 700 



34 



11 



620 



18 



1,910 



1,060 



87 



8 630 



46 



Year. 



1912.. 

 1913.. 

 1914.. 

 1915.. 



Total., 



August. 



240 



300 



September. 



170 

 170 



560 



10 



October. 



60 



60 



1,140 



1,270 



2,210 



530 



6,150 



631 



20 

 10 

 10 



12 



From Table V it vsdll be observed that the number of infected 

 bees found at different periods of the year varied considerably. 

 April and May furnished the highest percentage, being 18 and 17 

 per cent respectively. In March, June, July, August, and Sep- 

 tember the number of Nosema-infected bees among those examined 

 was 11, 8, 7, 5, and 10 per cent respectively. Out of 5,150 bees 

 taken from the apiary from April, 1912, to June, .1915, and exam- 

 ined, 631 (12 per cent) were Nosema infected.^ 



Laidlow (1911) reports that out of somewhat more than 1,500 

 bees received from various parts of Australia, 17 per cent were 

 found to be Nosema infected. 



From an examination of the foregoing tables it is seen that Nosema 

 infection was found to be present in practically every colony of the 

 apiary. Had further examinations been made of the few colonies' 

 in which Nosema apis was not found, one could well expect, from 

 what is known of the disease, that these, too, would have revealed 

 the presence of the infection. It is seen also that the infection 

 persisted throughout all seasons of the year, and that it was heaviest 



1 While this three-year study was teing made the apiary served for other work.. It is likely that the 

 attending manipulations were accoinpanied from time to time by a certain amount of robbing From the 

 nature of the disease, however. It Is not behoved that this fact aflected materially the results obtained 



