60 REPORT ON THE DISEASES OP SILKWORMS IN INDIA 



conditions — if they are favourable the disease is rampant ; if they 

 are not favourable the disease hardly shows itself, i Despite the 

 fact that muscardine was found by me only during the latter part 

 of the rains, there is no doubt that this is one of the most serious 

 pests, at least in Bengal. The rearers usually calculate on losing 

 about I of their crop during the September or November bunds 

 but it may be much more serious and frequently the whole rearing 

 is lost. 



What are the common sources of infection ? ( As infection 

 is spread only by the spores, an infected caterpillar becomes danger- 

 ous to others only after it is dead and covered with the white efflores- 

 cence. The spores being on the outside of the dead body they are 

 extraordinarily easily disseminated.; A rearing house and all the 

 furniture may thus become very highly charged with spores and so 

 infect subsequent rearings. The wind and the hands and clothing 

 of those attending on the diseased worms are the commonest means 

 of distributing the spores to a distance. /"The disease is very conta- 

 gious, and the healthiest caterpillars are as liable to be attacked 

 by it as are the less robust. The worms are said to be more liable 

 to attack during the moulting periods. Muscardine is not transmit- 

 ted hereditarily, for the worms attacked always die either before 

 # spinning or within the cocoon. ) 



Methods of protecting worms from the disease. When 

 muscardine makes its appearance in a rearing house early in the 

 rearing period the possibility of the worms being killed out by the 

 disease is very real, especially in hot humid weather when the fungus 

 develops most rapidly. If the disease does not reveal itself until 

 after the fourth moult some of the caterpillars affected may spin 

 but few may give rise to moths. As soon as a diseased worm is 

 seen in the litter, the litter should be changed as carefully as possible 

 and the old litter burned. The trays and rearing room should be 

 sprayed with 2-5 per cent, formalin, the strongest that can be afforded 

 — 1 per cent, while perhaps strong enough for routine disinfection is 

 not deadly enough to cope with an active outbreak. Next day the 

 litter should again be carefully Examined and if any dead worms 

 are found they should be removed and burned and the litter again 

 changed. As a routine, sulphur may be burned in the rearing room 

 daily for several days in succession until no more diseased worms 

 are discovered — about an ounce of sulphur mixed with a very little 

 saltpetre is sufficient for 100 cubic yards of space, the room being as 

 tightly shut up as possible. If a formalin spray cannot be used 

 sulphur may be burned instead — one or two pounds of sulphur mixed 

 with a few-ounces of saltpetre being burned for every 100 cubic 

 ards of space. Probably such proceedings could not be adopted 



