BARK-BEETLES; ENGRAVER-BEETLES. 



231 



the attacks of these insects, but if one does become seriously in- 

 fested it should be at once cut out and burned. It is certain to 

 die in a short time, and it is a constant menace to surrounding 

 trees from the abundance of specimens which will be produced, 

 ready to attack others at the least sign of weakness. Where a 

 slight infestation is noticed on a tolerably healthy tree, it should 

 be closely examined to ascertain the original source of weakness, 

 and when this is removed the tree should be stimulated by means 

 of appropriate fertilizers, and the trunk kept covered by white- 

 wash to which Paris-green has been added. Strong whale-oil 

 soap-suds will answer the same purpose, and a litt'e crude carbolic 

 acid will add to its effectiveness. In all cases the application 

 should be thorough, and should be kept intact until the tree has 

 fully recovered and is able to take care of itself. The beetle is 

 shown in Fig. 243, and its burrows in Fig. 244." 



The same line of treatment is adapted to other bark-beetles, 

 varied according to the differences in life-history. 



THE HICKORV-P.ARK BEETLE. 



(Scolytus ^.-spiiiosus Say). 



This beetle confines its work to all kinds of hickory, in which 

 it makes long and slender tracks under the bark, which radiate 

 from a primary, larger and vertical chamber (Fig. 235). The 

 beetle (Fig. 245), is entirely black, or black with brown wing- 

 covers ; the head above is flat, concave towards the tip ; the thorax 



Fig. 245. — Scolytus 4. spinosus, Say. 



Fig. 246. — Dendroctonus frontalis, 

 Zimm- After Division of Entomology, 

 U. S. Department of Agriculture. 



