82 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



they had a much higher mortality, which might be explained by 

 the handling involved in feeding, but the curious fact was that 

 frequently the dead caterpillars showed no organisms in gut al- 

 though they had all the external symptoms of flacherie. Further, 

 worms fed on the micrococcus frequently showed the bacillus only 

 after death. The organisms were also fed to mulberry caterpillars 

 (Experiment 24). None of the caterpillars thus tried died when 

 fed under normal conditions. 



On the whole it is to be concluded that flacherie in the muga 

 worms is very much the same thing as in the mulberry worms. 

 It is not an infectious disease, and it is brought on by some dis- 

 turbance in the metabolism of the caterpillar. What causes this 

 disturbance in the muga worm is evidently some sudden change 

 in the food. In the early weeks of the year (1921) in which the 

 outbreak I investigated occurred, the' weather was very dry and 

 there was but little fresh leaf on the trees when the newly hatched 

 worms were put on them. This seems to have caused a little 

 disease to appear. After the worms were partly grown a consider- 

 able amount of rain fell. There was a rush of new succulent leaf, 

 and then the disease began to show itself on all sides. It is not 

 unlikely that the temperature-humidity factor might come in here 

 too but I have no exact data regarding this. 



It is practically certain that these outbreaks of disease are 

 caused by climatic variations and vagaries, and for this reason it 

 would be very difficult to prevent rot diseases absolutely, but a 

 great deal can- be done to improve matters by developing a suit- 

 able type of food-tree — first selecting the best food-trees and then 

 studying the best method of cultivating them. A standard type 

 of tree grown as a cultivated plant and not allowed to go ahead 

 anyhow seems to me the most suitable form to aim at. There is 

 room for much excellent work in evolving this type of food plant 

 and in studying the best methods of cultivating it. Whether the 

 muga rearer would bother to take care of such a tree and prune 

 it and cultivate the ground round it is quite another matter, and 

 that must be decided by the authorities in charge. I am con- 

 fident that much improvement could be effected by rearing ex- 

 amined seed in a properly managed farm -or food-plant planta- 

 tion. It is possible too that the muga worm would respond to 

 rearing in a cooler, less hiumid climate than that of the Assam 

 valley. Wild Anthercea are found at Kalimpong at an elevation 

 of about 4,000 feet and there they spin the most excellent cocoons. 

 I understand the Sericultural Department in Assam is intending 

 to start a hill station at Shillong. It- will take several years to 

 grow the food plants and get the farm properly started, so that 



