DISEASES AND INSECT PESTS 219 



on the foliage, and when they become surfeited they 

 pass the quiescent state underground, or else they burrow 

 into the stems or midribs of the leaves. Every winter, 

 then, the gardener must remove the soil round each 

 bush which was attacked by Sawflies, digging as deeply 

 as he dare without injury to the roots. This is then 

 sterilised, or a new compost substituted. Insecticides 

 sprayed on the bushes will help to keep the flies away, 

 and will tend to prevent too extensive damage by the 

 larvae. The fUes are generally sluggish in dull, damp 

 weather, and hand-picking or netting will be most bene- 

 ficial. 



Hand-picking of the larvae is slow, tedious, and 

 scarcely profitable. In American gardens a sheet of 

 linoleum, slit to the centre, is kept smeared with grease, 

 treacle or tar. This can be easily placed below the 

 bushes in such a way that the stem is in the centre ; on 

 shaking the branches vigorously, many larvae fall on the 

 sticky mass, and may be killed or left to die there. A 

 gardener can speedily pass round a large border with this 

 apparatus, and the hnoleum wiU serve the purpose for 

 many years. A piece of stiff brown paper smeared 

 with treacle or gum serves excellently well for occasional 

 treatment. 



Hellebore extracts or arsenical washes are the only 

 substances which kiU the larvae. Thfe arsenical mixture 

 is best prepared by stirring one ounce of some arsenic 

 poison, such as Paris green, lead, or iron arsenate or the 

 like into some four or five gallons of lime water; keep 

 ^ stirring when spraying. Hellebore powder can be mixed 



