rilK WKSTKKN riNE-DESTRoYINC HA HK l!KKTLK. 29 



which must occur in large numbers before they can attack and kill a 

 tree. Some of the hvinj:: trees in the immediate neifjhborhood of th(^ 

 traj) trees maybe attacked by beetles attracted to tlu^ vicinity by the 

 felled or »^irdled trees. These should be felled mid trejited the same 

 as ti"a|) trees. 



If the conditions ajjpear to \\ arrant it, additional trees should be 

 girdled or felled about the first part of August to catch the .second 

 brood. These may l)e barked, to kill the l^roods, any time between 

 the first part of October and the first ])art of the following May. 



SUMMARY. 

 II.VBITS .\M) LIFE HISTORY. 



The westeiMi jiine-dest roving barkbeetle usually attacks and kills 

 the best examples of western yellow pine and sugar pine. 



If neglected and under certain conditions favorable to the species, 

 it is capable of devastating the jnne forests over large areas. The 

 broods of the beetl(> j^ass the winter in the outer ])ark of trees killed 

 by it the ]U'evious summer. The adults of the overwintering broods 

 einerg(^ and fiy in May. dune, and July, the beginning and ending of 

 the ])eriod varying with the seasons, latitude, and altitude. 



The first eggs from the first generation are dej^osited in .hine or 

 July, and in some of the warm localities po.ssibly as early as the middle 

 of May. In localities intermediate between the colder and warmer 

 regions the majority of the adults of the first j^eneration evidently 

 develop and emerge in August, but some individuals may remain in 

 the trees until June of the next year. 



The first eggs of the .second generation are evidently deposited in 

 August and S(>pteml)er, depending on locality, and it would ai)pear 

 that in intermediate localities all of the broods of this generation pa.ss 

 the winter (hibernate) in the larval stage in the outer bark. Tn the 

 warmer localities some of them nuiy develop and emerg(> in the fall. 

 >vhile in the colder localities there may be but one generation. 



The first evidence of attack on living trees is the presence of pitch 

 tubes (figs. 11 and 12, c) on the bark or of reddish borings lodged in 

 the crevices and around the ba.s(> of the tree. 



J)uriiig the fall, winter, and following sj)ring, after a >ur< osful 

 attack, the infested trees will be indicat(Ml by the fading yellowish 

 and reddish leaves. 



The Work of the insect will be indicated by the winding galleries 

 through the inner bark (fig. S). Trees from which the broods luive 

 emerged will be in(licat(>d by large luiiiiliers of small hohvs tluough the 

 outer bark (fig. 12). 



RE.MEDIES. 



The principal areas of infestation and the princi|)al |>atches of 

 infested trees should be located in Sepiend)er and ()clol)er. 



