REMEDIAL MEASURES. 177 



in order to stop larvae on their way to the crowns of the trees, 

 and starve them to death. They are .used chiefly against the 

 larvae of the pine-moth. High bands, 6 8 metres high, are 

 also made against young larvae that have just hatched out of 

 the nun-moth. 



(h) Clearance of infested areas. The whole wood may be 

 cleared and the soil thoroughly cultivated after burning all the 

 branches, etc., which are infested with larvae. This, of course, 

 is a last resort. The thorough cultivation of the soil is 

 necessary only when it is full of hibernating larvae or pupae, 

 Lophyrus rufus, Ratz., etc. 



(i) Spraying. Trees and plants in orchards or in forest 

 nurseries may be sprayed with certain substances to keep off 

 insects, such as lime-water, whitewash, potassium sulphide- 

 solution, decoction of tobacco, etc. A good recipe appears 

 to be 1 Ib. of pure unslaken lime, mixed with about 70 gallons 

 of water. The lime is slaked and then mixed with the 

 water and stirred up to form a milky fluid, which is allowed 

 to stand till the lime is deposited ; the water is then used on 

 the trees. The lime can be used again for five or six times 

 the quantity of water. The application is useful as long as the 

 insects are still in the larval or pupal stage. 



The sulphur solution is made by dissolving one part of 

 potassium sulphide in 500 parts of water, and the foliage is 

 sprayed with this solution. This drives all the caterpillars at 

 once from the tree, and sprinkled leaves escape further 

 damage ; five men in two days, with 38 Ibs. of potassium sulphide, 

 and the necessary water, can sprinkle 250 trees, at a total cost 

 of 50 shillings, or five trees for 1 shilling. 



The most valuable mixtures for tree-spraying are arsenical 

 washes or kerosene-emulsion. The former are made by stir- 

 ring about 1 Ib. of Paris-green or London-purple into 200 

 gallons of water, with the addition of a little flour or dextrin, 

 and keeping it constantly stirred during the operation of 

 spraying. As this mixture is poisonous, it cannot be used 

 where there is risk of injury to game. If it scorches the 

 foliage it must be further diluted. 



Kerosene-emulsion is made by emulsifying 1 gallon of 

 kerosene oil with half a gallon of boiling water in which a 



F.P. N 



