250 



doubtful value, and probably dangerous to other 

 colonies. But here again, such factors as the time of 

 year, the qualities of the queen, the amount of disease 

 in the vicinity, and even the prevalence of drones, must 

 weigh. I have known such stocks in a good year give a 

 satisfactory yield in stores, and come through the sub- 

 sequent winter, but it is impossible to tell to what 

 extent they have been instrumental in disseminating the 

 parasite amongst other colonies. If we judge stocks 

 from the point of view of their danger to other colonies, 

 such a type as is here referred to, is more to be feared 

 than one with a much higher percentage infestation and 

 an infestation of longer standing. The latter are 

 approaching the stage of definite uselessness and are 

 not usually worth saving, but the infestation appears 

 to be spent, and migration of mites to be more or less 

 absent. 



In bees of grade IIIc. to which I am now referring, 

 the tracheal tube may not only be blackened, but thick- 

 ened or encrusted internally with granular debris. In 

 such cases it is not unusual for the tube to be filled with 

 masses of decomposing material in which bacteria are 

 present. Amongst this, skins or moults of mites may 

 be seen, and frequently no living mites are to be 

 observed. 



Such conditions are also sometimes to be noted in 

 bees in which the tracheae are not markedly deterior- 

 ated, but in which there are many dead mites, but the 

 group in which this is a more or less common feature is 

 the one above referred to. 



Dead Mites within living Bees. 



An element of importance which must be recognised 

 and appreciated in endeavours to estimate the character- 

 istics of any infestation, is the presence of dead mites 

 within the tracheae of the bees. There appears to be 

 no doubt whatever that, the mites having performed 

 their natural functions of growth and mating, certain 

 of the females migrate to another bee host in which to 

 exercise the function of reproduction. Others remain 

 to multiply within the original host. Sooner or later 

 after fulfilment of the reproductive faculty, death 



