THE COLEOPTERA 149 



surface of the wood, partly in the inner bark, destroy the cambium or 

 growing layer, often entirely girdling the twig, branch or trunk as the 

 case may be, and causing its death. 



Control. — This must largely be accomplished by measures to keep 

 the trees as vigorous and healthy as possible. Any injured, broken 

 or otherwise affected limbs should be removed or so treated if possible, 

 as to restore them, and close watch of trees outside the orchard, liable to 

 infestation, should also be given. Infested trees which are still pouring 

 out gum can sometimes be saved by cutting back strongly and then culti- 

 vating and fertilizing freely. In some cases a thick coat of whitewash 

 mixed with a little table salt can be applied as a repellent for the beetles. 

 This treatment sometimes needs to be applied three times — once in 

 spring, again in midsummer, and once again in the fall. Washes of soap 

 and carbolic acid have occasionally been used with some success, and it is 

 claimed that the larvse can be killed in their burrows by using a carbo- 

 lineum spray material. This is made by dissolving 3 lb. of naphtha 

 soap in 3 gal. of hot water; adding a gallon of carbolineum, stirring 

 thoroughly and then diluting for use at the rate of 1 part of this to 4 

 of water. 



These methods should work equally well for any of the barkbettles 

 where the bark is no thicker than at the places where these insects 

 attack the fruit trees. 



