668 0. B. HARDENBERCx. 



acres in extent. When the writer visited this plantation a 

 few days after being notified, the disease had spread over 

 about one-tenth of the block, starting from the corner where 

 first noticed ; and in that aifected area I found 95 per cent, 

 of the bag-worms dead. A month later this plantation was 

 again visited, this time in company with the Government 

 Plant Pathologist, and we found then the entire block 

 infected, so much so that after a couple of hours' search 

 over the entii-e forty acres we could find only two live 

 bag worms. 



Later on, the same, or a very similar, disease was found 

 in the plantation of Mr. E. T. Hill of Seven Oaks, and 

 evidences of its presence have since been found at several 

 other plantations. 



The efforts to isolate and artificially propagate this disease 

 have thus far not been successful. 



All these diseases undoubtedly depend for their virulence 

 to a great extent on climatic conditions, and their efficiency 

 as a natural check to the bagworm therefore varies from year 

 to year. They constitute a factor which is as yet bej'ond 

 human control and thus must remain unsatisfactory. We 

 can artificially promote the spread of some of these diseases, 

 but cannot control their action. 



(6) The Cocoon. 



Toward the end of the feeding period, just before the 

 larva undergoes its last moult, it prepares for the pupation 

 by putting an extra inner lining to the bag. This inner 

 lining is very thin and closely applied to the original silken 

 covering. It serves to cover the irregularities of the inner 

 surface; and the inside of the bag, Avhich with increasing age 

 has become somewhat discoloured, is now clean, white, smooth, 

 and somewhat shiny. This inner lining made, the larva 

 moults into the last instar. After this no more food is taken, 

 and the caterpillar remains light in colour. Soon after its 

 moult it begins to spin its cocoon. This consists of a 



