£2 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



distressed at the occurrence, but that did not prevent their leaving 

 dead worms lying in the litter or throwing the litter, when cleaning 

 trays, anywhere outside, to help in the spread of the disease. The 

 matter is admittedly difficult, for the ryot cannot afford to spend 

 money on disinfectants — could not the sericultural departments 

 help here ? but surely he could change the litter frequently, burn- 

 ing it and any dead worms. If he will not help himself in very simple, 

 though somewhat laborious, ways, little can be done to assist him. 

 It is interesting to note that in this epidemic the better rearers 

 seemed to be suffering less than the more careless ones. 



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3. KIHI (FLY PEST). 



De finition and diagnosis. JQamage such as is caused by the 

 silkwornT rly to IsiTkworms is not always regarded as " disease " 

 in the strict sense. Doubtless when the parasite is large enough 

 to be seen with the naked eye one is tempted to look upon it as one 

 large animal preying on another and not as a case of disease caused 

 by a parasite. Yet the maggot of the silkworm fly is as true a 

 parasitemias the planont of Nosema bombycis or the mycelium of 

 Botrytis bassiana, (and the injury it causes is as much a disease in 

 one case as in the other/) We shall, therefore, very briefly consider 

 it here. 



(Worms attacked by this parasite show a very prominent black 

 wound-scar atHhe point where the maggot has entered the body of 

 the caterpillar. This wound remains open and forms the entrance 

 to a sort of chamber through which the maggot gets its supply of air. 

 This prominent black scar is so characteristic a feature that it alone 

 is sufficient for diagnostic purposes. One caterpillar may harbour 

 three or even four maggots and still live for some time. As a rule 

 worms are attacked only when they have passed the 3rd or 4th 

 moult. If the destruction of tissue is great the caterpillar will 

 not spin a cocoon, but if no very serious damage is done by the time 

 of spinning, the cocoon will be spun but the moth will never be 

 formed. Further, the cocoons thus got will be useless for reeling 

 as they will probably be pierced by a small hole through which the 

 larva of the parasite makes its way in order to reach the ground to 

 pupates) 



History. I have been unable to find any data referring to the 

 silkworm fly in the past — that is to say prior to the latter half of 

 the 19th century. As it is unknown in Europe this is hardly to be 

 wondered at. 



Life-history of causal organism. The Bengal silkworm 



fly — Ostrwa bengalensis (Tricolyga bombycis) — belongs to the Tachi- 



TVKid group of the true two-winged flies or Diptera. It is found only 



