REPORT ON THE DISEASES OF SILKWORMS IN INDIA Q$ 



in Bengal and Assam. In Japan a similar fly is found known as 

 Ugimya sericaria, and in China, Siam, etc., another closely related 

 form Tachina rustica. Toyama (1906) is inclined to the belief 

 that this last also occurs in India. The naming of all these flies 

 seems doubtful, and I have used the names that are given in the differ- 

 ent books and papers without verifying them so that they are pos- 

 sibly not the correct ones. It is considerably larger than a house 

 fly and is prominently striped in black and grey. It is very active 

 on the wing and makes a penetrating, buzz as it flies. Copulation 

 is said to take place in the air, and the female produces about 20O 

 eggs. (These are laid on caterpillars, being stuck on to the outside 

 of the skin.*) The egg is white in colour and though small can be 

 detected by the naked eye. It hatches in about 15 to 20 hours. 

 and ^he maggot, which emerges, eats its way into the tissues of 

 the caterpillar. The maggot lives on the tissues of the silkworm, 

 especially the fat body, and as mentioned above derives its supply 

 of air from the outside through the hole made by the maggot on 

 entering the caterpillar. The larva lives in the caterpillar for about 

 seven days and then proceeds to make its way out of the caterpillar. 

 If the caterpillar has spun in the meantime it cuts through the cocoon 

 and renders it useless for reeling. The maggot makes for the ground 

 and selecting a soft portion buries itself about an inch below the 

 surface and there pupates?) The pupal stage lasts about ten or twelve 

 days and then the (fly emerges ready to carry on a fresh life-cycle.\ 

 The times occupied in the various stages depend, of course, on the 

 temperature, etc. According to Cleghorn the pupae hybernate during 

 the cold weather. For further details of the life-history readers 

 are referred to the papers of Cleghorn, Sasaki and Toyama. 



Amount of the disease in India and loss caused by it. It 

 is very difficult to estimate accurately the amount of damage done 

 by this pest. Our census returns show that the fly may be practi- 

 cally absent from some rearings while others show 40 per cent- 

 infection (Appendices IA and IB). A great deal probably depends 

 on the care and skill of the rearer. \It must be admitted that on 

 the whole the fly is a very real danger causing a large amount of 

 damage each year, and that, while the whole crop is rarely lost by 

 it, it is quite possible that on occasions as much as about one half 

 of a rearing may be ruined through its ravages. The crawling 

 mass of maggots to be found sometimes under a heap of stored 

 village cocoons is a sight not easily forgotten, and a very striking' 

 proof of the prevalence of the fly and the damage it may cause?) 



* According to Sasaki (1886) the fly in Japan lays its eggs on mulberry leaf, and the cater- 

 pillar thus eats the eggs, which hatch out inside the worm. This does not seem to be tliv .-a^e 

 in Bengal. 



