APPLIED MICROSPORIDIOSIS 235 



be useful in tropical countries, if it could be trans- 

 ferred to insects concerned in the transmission of 

 animal diseases such as trypanosomiasis. Experi- 

 ments made by us in England have shown that 

 N. apis can kill blow-flies, house-flies, sheep-keds, and 

 certain butterflies and moths. But whether the whole- 

 sale sowing of Nosema would be advisable is very 

 problematic, and in England it certainly would not 

 benefit the citizen who uses honey for food, and 

 keeps bees for profit. Whether it could kill tsetse- 

 flies and be used successfully in tropical Africa for 

 this purpose, remains as yet untested, but is well 

 worthy of trial. 



