REPORT ON THE DISEASES OF SILKWORMS IN INDIA gg 



estimate of 25 per cent. loss. Amount of disease and loss from 

 disease are very nearly the same thing in India — in the case of 

 pebrine and sometimes muscardine the worms may spin cocoons, 

 so that all is not lost but the quality o£ the cocoons will usually 

 in these cases be very poor. On the whole it may be estimated 

 that in unexamined seed the amount of disease may vary from 

 100 per cent, to about 25 per cent. The loss from disease may 

 be about the same. In examined seed there may be practically 

 no disease of a preventible sort (pebrine) or at most a very low 

 percentage, but muscardine, grasserie and the fly may take a heavy 

 toll — up to 50 per cent, or even more — and there is a constant loss, 

 at times rising as high as 25 per cent., due to climatic vagaries and 

 bad rearing. 



3. What are the chief causes of disease in India ? The 



most deadly' silkworm diseases in India are pebrine and muscar- 

 dine. These are extremely infectious and are caused the one by 

 a protozoon, the other by a fungus. Now, while the spores of 

 these organisms are the actual agents by which these diseases are 

 transmitted, it cannot be denied that, to some extent at least, there 

 are other factors involved. In the forefront of these are to be 

 placed the lack of knowledge and the want of care shown so com- 

 monly by the Indian rearer. While sound seed will do much, it 

 will never completely compensate for bad rearing, and if the seed 

 is not of the best careless rearing will make the yield of cocoons 

 infinitely worse than it might have been. I am well aware that 

 poverty is to be blamed for much. The ryot cannot afford to alter 

 his rearing house to secure proper ventilation and he has not the 

 money to spend on disinfection, but he need not overcrowd his 

 worms or underfeed them however poor he may be. Here there 

 is a fundamental failing shown, and one that is not confined to 

 the East, for it is seen in Europe though to a less degree. Unfor- 

 tunately the Indian market does not seem to demand the best 

 cocoons — it is quantity and not quality that counts — and while 

 that is so, there will be no real inducement to produce a smaller 

 quantity of first grade cocoons rather than a large quantity of 

 poor grade stuff. 



The climate, at all events in Bengal and Assam, is another 

 potent factor determining the outbreak and spread of these diseases. 

 High temperatures combined with high humidity are not favour- 

 able to silkworm rearing, nor are droughts followed by downpours 

 of rain. These climatic disadvantages are particularly noticeable 

 in connection with the rot diseases, and indeed I am of the opinion 

 that these diseases are more or less directly to be referred to climatic 

 vagaries. But we have also seen that pebrine is more dangerous 



