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BACTERIUM CAMPESTRE IN SOUTH AFRICA. 



of Mr. D. Gunn, of the Entomological Division, and it is to 

 him that I am indebted for information with regard to insect 

 pests of cruciferous plants. 



During the summer cabbages are infested with the larvae 

 of the cabbage moth (Pltitelki cruciferarum), and slugs are 

 fairly numerous ; both these pests disappear in the winter. The 

 cabbage butterfly {Pliisia orichalccc) is known to occur, but is 

 not plentiful. During the winter months the Eagrada bug 

 {Bagrada liilaris) occurs very plentifully; it does not entirely 

 disappear in summer, but becomes so reduced in numbers that 

 it is a negligible quantity. The cabbage aphis (Aphis brassicce) 

 is also a great pest during the winter. 



Fig. 2. 



Smith has succeeded in transmitting the disease by means 

 of the larva of the cabbage butterfly (Pltisia orichalecc), so 

 there is every reason to suppose that the larva of the cabbage 

 moth {PlutcUa cruciferarum) is also capable of carrying the 

 infection. 



He has also found that the disease may be carried by slugs, 

 and Brenner reports successful transmission by aphides. It has 

 yet to be determined whether the disease can be transmitted by 

 the Bagrada bugs. 



Water-pore infections, however, are by far the most com- 

 mon ; during the summer weather a considerable number of 

 these frequently occur on a single leaf. 



