34 REPORT ON THE DISEASES OF SILKWORMS IN INDIA 



1. EAEER-coyEES. In one of the highly infected kutcha 

 houses some worms were kepi under a cover made from newspaper 

 (Experiment 10), and it was found that although the worms in the 

 open trays gave 125 per cent, disease those under the cover were free 

 from disease. The experiment was repeated with a similar result- 

 Thus it would seem to be possible to protect worms by merely 

 erecting a tent of old newspapers over them — by— pro t e cting 4 hem 

 from any dust that might contain spores of pebrine. 



2. I)isinpectants. (The most common method of destroying 

 infective germs'iiTby using some germicide or by letting in the sun 

 on them\ The rearers in this country have great faith in cow-dung 

 in this connection, and indeed there is a certain amount to be said 

 for it. That it has any germicidal effect I do not believe 

 (Experiment 13), but it serves to lay the dust — to fix the spores, if 

 there be any, to the floor, the tray or whatever is smeared with it, 

 and in this way may help to prevent the spores getting from the floor, 

 etc., on to the food of the worms. The smoke from the domestic 

 fire is also claimed to be a good germicide. Moveable objects such 

 as trays in the rearing houses are usually exposed to the sun and it is 

 reasonable to expect that this might have some effect. Experiments 

 were designed to test this. Some pebrinised material was exposed to 

 the sun for a whole day and then fed to caterpillars as leaf smears. 

 The material exposed to the sun gave no disease, while the unsunned 

 control gave 17 - 5 per cent, disease. Material kept in a closed 

 wooden box, which was exposed to the sun, gave the same result as 

 the material exposed directly to the sun (Experiment 11). Next 

 two bamboo trays were smeared with infective material and one 

 was exposed to the sun while the other was kept.in-doors. This 

 experiment was repeated five times (Experiment 12). On one 

 occasion the sunned tray gave no disease while the unsunned one 

 gave 15 '8 per cent. In the other cases the sunned trays gave consi- 

 derably less disease than the unsunned one. On the whole probably 

 exposing the furniture of the rearing house to the sun is of some use 

 and is to be recommended. 



Solutions of copper sulphate of about 1 or 2 per cent, strength 

 were long used as the standard disinfectants in sericulture, but with- 

 in recent years this has been abandoned in favour of a solution of 

 " formalin " in water. I understand that the Japanese use this, and 

 the French sericulturists, so long wedded to copper sulphate, also 

 have found forma 1 dehyde more useful. I used three methods of 

 testing these germicides : (1) infective material in the form of a 

 powder was sprayed or otherwise treated with the germicides and the 

 treated material was fed to worms ; (2) trays and cages smeared with 

 infective material were treated with the germicides and then cater- 



