REMEDIES AGAINST FOREST INSECTS. 35 



aud the conditions of application also vary greatly. Unleached wood 

 ashes should not be applied too freely in contact with the body of the 

 tree or the roots, since water leaching through them may contain pot- 

 ash enough to injure the plant. Lime in any reasonable quantity could 

 hardly cause injury. The application of either of these is generally 

 beneficial and tends to destroy and repel insects from the base and roots 

 of trees. The ashes act benflcially as a fertilizer. 



Coal Ashes and coal Dust. — Coal ashes and coal dust have been used 

 for this purpose, but their effects could only be mechanical, aud, while 

 doubtless of value to the plant as a mulching, could have but little 

 effect on insects. The beneficial effects of either of these used dusted 

 on the plant are doubtful, except in cases of soft-bodied slugs (saw-fly 

 larvae), where their action is generally good. 



Pyrethrum, Hellebore^ Sulphur. — These well known insecticides may 

 be used in powdered form or may be mixed with water and applied in 

 a spray. While they can not be recommended for general forest work, 

 cases will frequently arise warranting their use in a limited way against 

 aphids and other soft-bodied insects. Hellebore is of especial value 

 against saw-fly larvfe. Sulphur is a valuable agent against the red 

 spider {Tetranychus telarius) aud may be used alone or in connection 

 with emulsion of kerosene. 



Alkaline Washes : potash Lye and soda Lye. — Alkaline washes are 

 solutions of crude soda or potash, or soap preparations of these sub- 

 stances. Concentrated soda or potash lye can be purchased at the 

 stores, and are often used as washes tor aphids and coccids with con- 

 siderable success. Of these the potash lye is to be preferred, as its 

 action on the tree is not so harmful as the soda lye. The best possible 

 source of a caustic wash is the potash lye leached from wood ashes- 

 Crude lye washes should be used with caution, since when too strong 

 it injures both branches and foliage. Definite statements as to the 

 strength to be used can not be made. The different brands of concen- 

 trated lye vary much in composition, so that it will always be advisable 

 to make test applications before general work is attempted. In the 

 preparation of washes, one can (1 pound) of lye is dissolved in from 3 

 to 5 gallons of water; the stronger solution is very injurious to tender 

 plants, and even the weaker one is entirely too harsh for a safe wash ; 

 yet, if diluted much more, its effect on the insect will be impaired. 

 The same quantity of lye used in the preparation of a soap will give 

 better results, aud its use will not then be attended with like danger 

 to the plant. 



Alkalijie Washes : Soaps. — Soap preparations are made from either of 

 the above lyes with grease or oils of any kind and in my experience are 

 much preferable to the crude lyes. 



Any soft or jelly soap makes a good wash for Aphides, and for this 

 purpose need not be strong ; for Coccids the strength should be greater. 

 The preparation known as " whale-oil " soap has a more or less stand- 



