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They commence injury by gnawing the outer layers of the 
young roots, afterwards making tunnels inside the main 
root; they may also invade the lower part of the stem. 
The pupe are about 4in. long, oval in form, a light or 
dark brown and are found in the soil close to the plants. 
As regards preventive measures early plants have the best 
chance of success as they become well set before the bulk 
of the Flies appear. Earthing the soil around growing 
plants is valuable as it causes the development of fresh 
rootlets, which serve to replace those already destroyed 
by the maggots. A cupful of paraffin well mixed with 
each bucketful of sand, sprinkled round the plants once 
a week until good growth is made, is to be recommended 
and it acts as a deterrent, driving the Flies elsewhere. 
Dusting the young plants with soot is said to be effective 
and is well worth trial. In America tarred felt paper discs, 
slipped round the stems of the young plants and pressed 
flat on the ground are strongly recommended. They are 
said to afford efficient protection to young plants against 
the Flies laying eggs thereon. Experiments are being 
conducted under my direction to test the value of these 
discs, and if they prove satisfactory, their low cost and 
the simplicity of the method will argue strongly in their 
favour. When the crop is infested much benefit is derived 
by pulling up and burning all infected plants as soon as 
noticed. Furthermore, all cabbage stumps should be up- 
rooted straight away and not left to decay; by these 
means large numbers of larvae are destroyed which would 
otherwise escape into the soil to pupate. In very severe 
infestations I would strongly advise discontinuing grow- 
ing cabbages for one year, and replacing with peas and 
beans or other distantly related crops. Unless some such 
course be taken bad infestations may continue for several 
years in succession, owing to the large number of pupz 
the soil contains during the winter, after the season is over. 
Such pupee are very hard to get rid of as soil dressings 
such as lime or gas lime are of very little value. Digging 
over the soil exposes considerable numbers of pupz to 
the attacks of insectivorous birds, while over large areas 
deep ploughing might possibly effectively bury a large 
proportion of them. 
The Onion Fly (Hylemia cepetorui) (17) 1s closely 
related to the Cabbage Fly and is a common pest wherever 
onions are grown; it is a greyish Insect very like the 
