aoo 



CONTROL OF WATTLE liAGWOEM. 



Tliese two experiments caniiot be regarded as coiifhisive, 

 but they indicate that the disease is contracted throngh the 

 ingestion of contaminated food and that the virus is filterable. 

 One difficulty lias still to be cleared up, and that is the manner 

 in which the disease is spread in IN'ature. The larva dies and 

 dries up inside the bag, hence it is difficult to understand how 

 the foliage becomes contaminated with the virus of the disease, 

 unless it be through the faeces, but the alimentary canal is 

 the last of the organs to be attacked, and no nolyhedra are 

 found in the intestine right up to the death of the larva. 



There are other diseases of an obscure nature to which the 

 bagworm is liable. The affected larvae die and disintegrate 

 into an evil-smelling liquid, which soils the bags and teems 

 with bacteria. Whether these diseases are due to bacteria or 

 to disturbances in the normal physiological functions, or both, 

 is at present undertermined. On several occasions I have come 

 across sickly larvae which, on being disturbed. Imve discharged 

 a drop of brownish liquid from their mouths. This fluid is 

 found to contain large numbers of bacteria, tlie great majority 

 of which are bacilli, with large, oval, terminal sjjores. These 

 larvae die and disintegrate as above, but, until the bacteria 

 have been isolated in pure culture and inoculation and feeding 

 experiments performed with them, no definite assertion can 

 be made as to the existence of a bacterial disease. 



In the figures given below all the bagworms that have died 

 of diseases other than the fungous disease are added together. 

 This is unavoidable, as Haines' records do not distinguish 

 between wilt and other diseases, but I have records whicli show 

 that of the bagworms collected at Mountain Else 6 per cent, 

 were killed by wilt disease, and of those collected at Hilton 

 Road no less than 19 ])er cent, died of this disease. 



Although the climatic conditions at Hilton Road are such 

 that one would expect the fungous disease to flourish there, 

 only 2 per cent, of the 800 bagworms examined were found 

 to have succumbed to this disease. This would appear to be 

 entirely due to the scattered manner in whicli the bagworms 



