REPORT ON THE DISEASES OF SILKWORMS IN INDIA 83 



results cannot be hoped for at once, but this is certainly a very im- 

 portant line of investigation and should be thoroughly explored. 

 The ease with which muga worms seem to take flacherie might 

 possibly point to some weakening of natural resistance, and all 

 methods of increasing this resistance should be tried. 



The question of attempting to completely domesticate the muga 

 caterpillar is a very interesting one. In Basu's report (1915) it is 

 said that there is no record of this having been done. I have done 

 it on a very small scale in Kalimpong, but I very much doubt if 

 the results so far got justify the continuance of the experiment. 

 The worms I reared, although they spun cocoons, were not parti- 

 cularly healthy, and it must be remembered that any weakness 

 will probably be intensified by the rather unhealthy life indoors, 

 while parasitic diseases, which are at present relatively of little 

 importance, would get an opportunity of flourishing. It seems to 

 me that the muga industry can best be served by an intelligent 

 modification of the methods already in uses If the muga is really 

 a very mixed race, as has been suggested (See footnote, p. 80) it 

 would undoubtedly be advisable to try to breed true races. 

 These might be more reliable than the present mixtures. It is a 

 point that should be investigated. 



Muga worms are also said to suffer from grasserie — called " phula- 

 rog " in Assam. I have not come across any muga worms suffering 

 from this disease, but from the symptoms given by Basu (1915) 

 there can be no doubt about the diagnosis. On the whole it seems 

 to be of much less importance than flacherie, only 31 cases being 

 given in the appendix on disease in that report as compared with 

 124 cases of flacherie. In Appendix V of the same report there is 

 a note on grasserie in which the loss is given as 4 per cent.- In 

 this appendix too the polyhedral bodies characteristic of grasserie 

 are said to be oval and different from the crystalloids found in 

 cases of grasserie in other silkworms. The disease is also said to 

 be contagious. This last statement is extremely doubtful, and I 

 should also doubt the opinion that the polyhedral bodies of grasserie 

 in muga are different from those in other silkworms affected with 

 grasserie. As I have not seen any cases of grasserie in muga, 

 however, I cannot express an absolutely authoritative opinion. I 

 think it may pretty safely be taken, however, that if not exactly 

 the same as grasserie in other worms it is for all practical purposes 

 similar — brought about by food and temperature conditions and a 

 sequel to other diseases just as in the case of the mulberry worm. 

 It is a disease in the same class as flacherie, not infectious or heri- 

 table but directly or indirectly traceable to climatic" conditions. 

 Improvements in the rearing of the worms such as have been 



