342 WEST VIRGINIA EXPERIMENT STATION 



once new subjects for investigation and complications that had 

 not been expected, which would possibly necessitate a change 

 in the plans of conducting the experiments with the imported 

 insects. The extent of the mortality of the destructive species 

 was to be determined, and if possible, the causes of their 

 death ascertained. I had found the destructive species 

 dead in the trees in the norther part of the State, and here the 

 same condition was found in the opposite or southern portion 

 which indicated that possibly the species had been extermi- 

 nated throughout the State, and that unless the timber con- 

 tinued to die from some other cause, the trouble must come to 

 an end. But in the great number of other species of bark bee- 

 tles, two or three of which it was thought were capable of at- 

 tacking and killing the trees on their own account, there was a 

 serious complication. 



OTHER BARK BEETLES THREATENING THE TIMBER. 



Indeed, it seemed as if the timber must continue to die with 

 the enormous numbers of Dendroctonus terebrans and Hylur- 

 gops glabratus found attacking the base and roots of dying and 

 living trees. With Tomicus calligraphus to attack as it was 

 the lower portion of the trunk; with swarms of Tomicus pini 

 and T. caelatus to invade the upper portion of the trunk and 

 tops; with Pityogenes plagiatus to attack the small branches; 

 and still other species ot bark and twig beetles, to attack the 

 terminal twigs and other portions of the tree; with two or three 

 species of timber beetles 1 to perforate the sapwood; and the 

 numerous species of flat headed (Buprestid) and round headed 

 ( Cerambycid) borers mining into the bark and wood of the in- 

 jured and dying trees, it seemed that there was no chance for 

 the remaining timber to escape. The only species, however, 

 fehat was found attacking trees that were not injured in any 

 way and not infested with any other insect, was the turpentine 

 bark beetle Dendroctonus terebrans. In some sections scarcely a 

 tree could be found that had not been attacked by this species 

 always, however, in the bark at the base of the tree or the ex- 



l Xyloterus bivittatus X, retusue and Onathotrichus materiarius. 



