13 



the stains left by ambrosia beetles probably entail more serious lo 

 than their direct attacks upon living trees. 



The majority of the species confine their depredations to the sap wood 

 of recently felled or dying trees. They therefore affect injuriously the 

 least valuable portion of the wood. On the other hand, some of the 

 larger and stronger species are capable of entirely destroying for any 

 useful purpose except for fuel the timber of the largest trees. Their 

 borings penetrate the heartwood in every direction and riddle it with 

 holes. 



Occasional black holes and stains left by these beetles in the heart- 

 wood of timber otherwise sound reduce its grade and its value in the 

 market, and render it unfit for use where the full strength of the 

 material is required, as, for example, in the framework of buildings and 

 the construction of wagons, agricultural implements, etc. But for some 

 other purposes, as for furniture and inside finishing lumber, it is not 

 necessarily deteriorated. 



The damage to timber intended for use as cask headings, staves, shin- 

 gles, and the like is very serious. Cask makers frequently repair the 

 damage when not too extensive by closing the holes with wooden pins. 

 The holes made by certain species of timber beetles can not be plugged, 

 but in most cases, owing to the uniform system followed by each spe- 

 cies in constructing its galleries, a particular method of sawing is capa- 

 ble of reducing the damage to a minimum and of effecting a very 

 considerable saving of material. 



REMEDIES. 



From what has been said of the nature of the food of these beetles. 



it is evident that any method by which the entrances to their galleries 

 in the bark can be closed will effectually put an end to the progress of 

 their colonies. 



Perhaps the best means of accomplishing this is by coating the 

 trunks with dendrolene or raupenleim. A light brushing or spraying 

 of the bark with creosote or kerosene will sometimes accomplish the 

 same result, especially at the beginning of an attack. But this can 

 not be depended upon to permanently protect the trees. 



Valuable fruit trees which have suffered injury from fire or frost can 

 not always be protected from attacks of the borers by coating the bark. 

 because of the risk of injury to the buds, which must be allowed to 

 grow upon the trunks. In such cases, if borers enter the wood their 

 holes must be plugged. An excellent method is to insert an iron wire 

 as far as it will go, cut it off and Leave the piece in the hole. The 

 inhabitants of colonies thus imprisoned are unable to extend their 

 borings and inevitably perish. 



