200 PLUM. 



infestation. If infested trees are found to be dying, they 

 should be cut down and burnt ; and boughs or twigs, such as 

 that figured at p. 199, should be cut off also and burnt. 



Where there is only moderate attack, the trees should be 

 gone over to ascertain what is needed, and treated accordingly. 

 The time of the emergence of the beetles may be known by 

 the appearance of the little perforations like shot-holes in the 

 bark, and the fine dust from the workings of the insect that 

 has fallen from them. In the case of the pieces of branches 

 which were sent me there was a good deal of this " frass " 

 thrown out. Where the Xylehorus or Shot-borer Beetles are 

 also present, it may be necessary to strip some small pieces of 

 bark to ascertain whether the "shot-holes" are caused by 

 "borers" whose tunnels will be found, as with the Scolytiis 

 under consideration, lying (probably in great numbers) super- 

 ficially on the outside of the wood, and beneath the inner 

 coat of the bark, and only occasionally entering the wood for 

 a very short space (see p. 199) ; or, like the Xylehori, piercing 

 into the solid wood before commencing further damage. 



Various washes have been recommended to prevent per- 

 foration of the bark by the beetles for egg-laying purposes, of 

 which one of the most likely to be successful is that recom- 

 mended by Dr. W. Saunders, Director of the Experimental 

 Farm of the Dominion of Canada, for prevention of various 

 kinds of fruit-tree bark-borers. This consists of soft-soap 

 reduced to the consistency of a thick paint by the addition of 

 a strong solution of washing-soda in water; "this, if applied 

 to the bark of the tree, especially about the base or collar, 

 and also extended upwards to the crotches, where the main 

 branches have their origin, will cover the whole surface liable 

 to attack ; and if applied during the morning of a warm day, 

 will dry in a few hours, and form a tenacious coating not 

 easily dissolved by rain." * A protective coat of this mixture 

 given when the beetles are emerging (which may be known, 

 as above mentioned, by the frass, or wood-dust, thrown out 

 from their borings), and another application somewhat later, 

 would most likely answer well. 



For special application where it is desired to protect valu- 

 able trees from infestation. Dr. Taschenberg recommends the 

 use of Leinweber's mixture. A recipe for this will be found 

 in Prof. W. E. Fisher's useful work referred to below t : — 

 " Five pounds of tobacco mixed with half a pailful of hot 

 water, kept hot for twenty-four hours ; the water is then 



* See 'Insects Injurious to Fruits,' by W. Saunders, F.R.S.C., &e., p. 19. 



t ' Forest Protection,' by W. R. Fisher, Assistant Professor of Forestry, 

 lioyal Indian Engineering College, Cooper's Hill, &c., p. 250. London : 

 Bradbury, Aguew & Co., Bouverie Street. 1895. 



