74 REPORT ON- THE DISEASES OP SILKWORMS IN INDIA 



bacteria are quite clear upon the point that some initial distur- 

 bance is necessary in the caterpillars before the disease can start. 

 There are many causes which are blamed for this metabolic dis- 

 turbance, such as careless handling and conservation of the seed, 

 bad food, overcrowding, bad ventilation, etc. To me it seems that 

 the most important factor is the temperature-humidity one. When 

 both temperature and humidity are high then flacherie is to be 

 expected. I would lay the greatest stress on ventilation and pro- 

 per spacing of the worms. It may, however, be safely assumed 

 that whatever makes for the general health and well-being of the 

 worm will help to prevent flacherie. 



To attempt to keep the worms from ingesting the incrimi- 

 nated bacteria would be fruitless. Attempts have been made 

 (Carini) to feed worms on disinfected leaf but the worms so fed 

 showed much more disease than those fed normally. The dis- 

 infection of rearing rooms is always to be commended, but I am 

 very doubtful if it is of much value in connection with flacherie. 

 In France, 1 or 2 per cent, formalin is being used for this purpose. 

 In Kashmir the rearing houses are not disinfected at all, and they 

 seem to be no more — if as much — subject to flacherie than in 

 France itself. 



Do conditions in India make the disease specially dangerous 

 or difficult to check ? Flacherie is not of very great importance 

 in India despite the fact that the climate for several months in 

 the year might be expected to be extremely favourable to its 

 development. The multivoltine worm, as I have shown in my 

 experiments, is evidently very resistant to gut diseases of this 

 type. Possibly many centuries of somewhat searching treatment 

 have eliminated all but the most resistant races. Univoltine 

 worms reared in the plains of Bengal alongside of multivoltine 

 worms, in the same room and under the same conditions, tend to 

 die off completely from flacherie, while the native worms do not 

 suffer at all. If the univoltines are fed on tree mulberry they do 

 not suffer so seriously, and if great care is taken it is quite possible 

 to rear univoltines from European seed. The point is, however, 

 that the multivoltine worm can stand the normal Bengal condi- 

 tions while the univoltine cannot — we are therefore justified in 

 assuming that one of the chief reasons that flacherie is not very 

 important in India is that the Indian worm is very resistant to 

 this disease. According to Mukerji, "the principal causes of 

 flacherie do not occur in Bengal." These are : — (a) " seed getting 

 spoilt" — in the multivoltine worms seed is kept for so short a 

 period that it is not likely to go wrong. (6) " Hereditary tendency " 

 owing to the habit of the Bengal rearers in seeing the worms 



