1920] ECONOMIC ZOOLOGY — ENTOMOLOGY. 59 



for from 21 to 31 hours. When suspended in water, B. ijluton was destroyed 

 by the direct rays of the sun in from 5 to 6 hours. Wlien suspended in honey 

 and exposed to the direct rays of the sun, B. pluton was destroyed in from 

 3 to 4 hours. In the presence of fermentative processes in a 10 per cent sugar 

 solution B. pluton was destroyed in from 3 to 5 days at incubator temperature 

 and in from 11 to 21 days at room temperature. In a fermenting honey solu- 

 tion outdoors B. pluton was still alive and virulent after one month. In the 

 presence of putrefactive processes at incubator temperature B. pUiton was de- 

 stroyed in from 7 to 13 days and at room temperature in from 21 to 35 days. 

 In a putrefying medium at outdoor temperature B. pluton remained alive and 

 virulent for more than 40 days. The maximum period has not been deter- 

 mined. In honey at room temperature B. pluton ceased to be virulent in from 

 3 to 7 months. Mixed with pollen, B. pluton remained alive and virulent 

 for more than 7 months at room temperature and more than 10 months at 

 refrigerator temperature, the maximum time not being determined. In 0.5 

 per cent carbolic acid solution B. pluton was destroyed in from 8 to 18 days ; 

 in 1 per cent it was destroyed in from 5 hours to 4 days, and in 2 and 4 per 

 cent in less than 6 hours. The probability is that at these higher strengths 

 of the solution minutes rather than hours are sufficient for the destruction of 

 the virus. Experimental evidence indicates that at the present time drugs 

 should not be depended upon in the treatment of European foulbrood. 



" Robbing from diseased colonies of the apiary or from neighboring apiaries 

 is the most likely manner in which European foulbrood is transmitted in nature. 

 Brood combs containing diseased brood, if given to a healthy colony, serve as a 

 medium for the transmission of the disease. European foulbrood is not likely 

 to be transmitted by queens or drones. Whether they ever do so has not been 

 demonstrated. As a rule a hive which has housed a European foulbrood colony 

 should not be considered as a fruitful source of infection. The facts indicate 

 that often such hives could be used with impunity for housing colonies without 

 treatment. Flaming them inside certainly removes all danger. The transmis- 

 sion of European foulbroed by way of flowers, visited by bees from diseased 

 colonies and subsequently by those from healthy ones, is not to be considered as 

 a likely source of infection. W^hether the water supply is ever a source of 

 danger is not known. It is evidently not a fruitful source. The disease is not 

 likely to be transmitted through the medium of the clothing or hands of the 

 apiarist. Tools and bee supplies in general do not serve as means for the trans- 

 mission of the disease in the absence of robbing from such sources. 



"It is usually possible to diagnose European foulbrood from the symptoms 

 alone. A definite diagnosis can be made from suitable samples by bacteriologi- 

 cal methods. The prognosis in European foulbrood varies from very good to 

 exceedingly grave. The tendency for a colony to recover entirely from the 

 disease is much greater than in American foulbrood. Considered from the 

 technical point of view, much is yet to be learned concerning European foul- 

 brood. For practical purposes, however, it can be said that sufficient knowledge 

 has been gained to make it possible for the beekeeper to devise a treatment 

 which will be logical, efficient, and at the same time economical." 



A list is given of 20 references to the literature cited. 



Nosema apis in hive bees, J. Rennie and E. J. Harvey (Scot. Jour. Agr., 2 

 {1919), No. 4, pp. 511-532). — The authors differ from the view that N. apis is 

 the cause of Isle of Wight disease. " Our main conclusion from a study of the 

 presence of N. apis in bee colonies in this country is that this parasite is always 

 a weakening factor, and in the presence of other adverse conditions favorable 

 to the development of dysentery it may become serioi^sly pathogenic to bee 

 stocks. In ordinary circumstances we have not found i(n:o destroy bee colonies 



