52 REPORT ON THE DISEASES OP SILKWORMS IN INDIA 



(Banks, 1911), but as a rule in India about six bunds are got 

 — March, April, May-June, July, August-September, October- 

 December. The rate of development of the worms varies very 

 greatly according to the time of year, that is to say, according to the 

 temperature. The eggs take from 7-12 days to hatch, the caterpillar 

 stage lasts 3 to 4 weeks, and the pupal stage 10-16 days. The moths 

 couple very shortly after cutting out. The whole cycle takes from 

 5 to 8 weeks. In the univoltine worm, the life-cycle lasts a year — 

 the eggs stage about 10 months, the caterpillar stage about 5 weeks 

 and the pupal stage about 2 weeks. 



Now in the first place the constant succession of broods through- 

 out the year in India undoubtedly makes it more difficult for the 

 sericulturalist to keep disease at bay. The rearing houses are never 

 long enough vacant to let any pebrine spores that may be present 

 in it die out — we saw that at least 3 months were necessary for 

 this — and consequently disinfection must be resorted to. The short 

 space of time between the laying of the egg and its hatching is also 

 at least inconvenient, for it leaves a very short time for moth exami- 

 nation — days only where in Europe they have months. A great 

 deal is made of this in India, but personally I cannot see that it is 

 so very serious a matter, as I do not believe that the supposed 

 increase of spores in the moth is of much importance. I have already 

 discussed this question in part (p. 23), but I wish to return 

 to it here. Experiment 22 shows the results of examining a 

 series of moths from the time of cutting out up to the time when 

 examination usually takes place, and it will be seen that spores 

 were present in greater numbers than developing forms from the 

 very start, so that infection could have been detected on the day 

 of cutting out. It is evident to me that if sufficient spores are 

 not present to make the infection detected on the day after the 

 moth lays its eggs, the infection must be so slight that it will not 

 be likely to cause any harm. It seems better worth while to risk 

 an occasional very mildly infected moth being undetected by 

 beginning the examination early than to " rush " the examination 

 in one or two days when more highly infected moths are even 

 more likely to be overlooked in the hurry. I can find no evidence 

 to show that sp^re-formation does not take place abundantly in 

 ten days. All this fuss is the result of Mukerji's erroneous ideas 

 about the development of Nosema — Hutchinson (1920) evidently 

 accepts as evidence ''the experience of seed rearers in Bengal " 

 but that of course is merely the result of Mukerji's teaching. My 

 experience is that in the hot weather and rains — when the moths 

 have to be examined according to this idea in about two days — 

 five days having to elapse after laying before examination is begun 

 — at that time abundant spore-formation takes place, as has been 



