64 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



Methods of protecting worms. The obvious method of pro- 

 tecting the worms is to keep the fly out of the rearing room. But 

 despite the large size^ of the fly and its characteristic note this is 

 not so easily done. <TJie method employed by the ryot is to keep 

 the rearing room in comparative darkness so that the fly may not see 

 its victims. ")This is not a desirable measure and it is extremely 

 doubtful if it is very effective — it is stated by Toyama (1906) that 

 the fly loves shade. In the Government nurseries wire-gauze is 

 used for covering the windows and ventilators, and special " fly- 

 killing rooms " are provided at the doors. This seems to be fairly 

 effective as the number of fly-blown cocoons from the nurseries 

 is small, but it is doubtful if the village rearer can afford to use 

 wire-gauze, and if he would take the necessary trouble to ensure 

 success in using it. The practice of rearing only every alternate 

 bund seems to be a good one, but it is not rigidly practised, and 

 even if it were it would not stamp the pest out as doubtless the fly 

 can use other hosts — according to Toyama (1906) in Siam the fly 

 is a common parasite of caterpillars other than silkworms. It is 

 possible that wood smoke may help to keep the fly away, and as 

 the damage is done only towards the end of the life of the worm 

 it ought to be possible to keep a smoky fire burning during this 

 time in the entrance to the rearing room. Of course all maggot- 

 infected worms and cocoons should be at once burned or otherwise 

 destroyed. Mukerji (1899) described various methods by which 

 attempts may be made to keep the fly down. The parasitic " midge " 

 described by Cleghorn (1887) might be encouraged and traps for 

 attracting and killing the flies might be devised. It is very possible 

 that the flies are attracted by certain odours, which might be used 

 to lure them to their destruction. It seems to me that there is 

 room for an entomologist to investigate this problem afresh and to 

 try to devise methods for protecting the rearers' houses against the 

 fly. The Government rearing houses, protected by their wire- 

 gauze, are in a fairly satisfactory position — as usual it is the ryot 

 who needs some simple and cheap means of protection. That 

 the fly will ever be exterminated is more than is to be expected, 

 but measures for its control ought to be tried along the lines men- 

 tioned above. 



In Siam, according to Toyama, the rearers wrap a piece of cotton 

 cloth round each basket of worms, and in China mosquito netting 

 is used on the doors and windows. 



4. EOT OR WILT DISEASES. 



The diseases with which we have been dealing up to the present 

 are caused by very definite and easily recognized parasites, and 



