BEES IN COLONIES AFlfECTED BY EUROPEAN FOULBROOD 



23 



Table III. — Average time, under various conditions, in which disease hecomes 

 apparent in a colony after infection with Europecm foulbrood. (Averages 

 taken from Table II) 



Before the 



heavT 

 honey now. 



Colony G, hybrid.... 

 Colony F, Italian.... 

 Average of these two, 



Days. 



7i 



During 

 the heavy 

 honey flow. 



Colony H, hybrid 



Colony A, Italian 



Colony I, Italian 



Average of these three 



Days. 



8i 

 9 



8{i 



Becurrence 

 of disease, 

 after treat- 

 ment, dur- 

 ing honey 

 flow. 



Colony J, hybrid originally 

 Colony F, Italian originally. 

 Average of these two 



Days. 



9i 



The data shown, particularly in Table III, tend to disprove the 

 theory that Italian bees have a natural immunity or resistance. If 

 a larger number of observations could have been made, the variation 

 would have appeared less. The effect of the honey flow is evident, 

 however. 



When it is a question of the age at which the larvae are fed material 

 that contains infection, these figures are significant. In the life 

 history of the bee, 3 days are spent in the Qgg and from 5 to 6 days 

 as larva before capping, making a period of 9 days in all. After 

 3 days in the egg and after having been fed predigested food for 3 

 days, with the additional 24 to 48 hour period of incubation, as 

 was observed earlier in this paper, the larva ought to show disease 

 from the fourth to the fifth day after hatching, or the seventh to 

 eighth day of its existence, if Von Planta's assumption is correct. 

 From actual observation this was found to be true and from observa- 

 tion of the averages in Table III it is seen that the first appearance 

 of disease occurs between the seventh and ninth days, varying with 

 the conditions of the honey flow. 



Eeferring to Dr. Miller's theories, it is hard to believe that there 

 is not plenty of highly infectious material left in the colony after 

 a 5 or 6 day period of queenlessness. Aside from actual observations 

 of moist, yellow, melting larvae present more than 6 days after the 



