23 



evidence will enable anyone who lias given the subject some atten- 

 tion to determine that such trees were attacked while living. 



After all of the bark has fallen from the trunk of standing or felled 

 trees, the characteristic grooves in the surface of the wood, made by 

 the beetle when the primary galleries were excavated, are often quite 

 conspicuous, even on trees that have been dead for fifteen to twenty 

 years. 



WOODPECKER WORK. 



Another, and indeed oue of the most conspicuous evidences of 

 the presence of the spruce-destroying beetle, is found in the work 

 of woodpeckers on the middle trunk of the dying and dead trees. 

 Scarcely an infested tree escapes the bird, and the outer bark removed 

 by them in their search for the insect gives such trees at first a red, 

 and later a smooth, light-grayish appearance, which is very conspicu- 

 ous. Even living trees infested by the insect can be recognized by 

 this means at a greater distance in the woods than by any other of 

 the conditions mentioned. It must be remembered, however, that all 

 spruce trees showing the work of woodpeckers are not necessarily 

 infested by the spruce destroj^er. For, as in the case of trees which 

 have been infested with other bark beetles, or the flat-headed and 

 round-headed borers, the birds scale off the bark in the same or a similar 

 manner. Examples, however, of trees dying from the work of these 

 secondary enemies are rarely met with. Therefore the work of the 

 woodpeckers, especially in the Maine woods, is quite reliable evidence 

 of the presence of the spruce destroyer. 



A COMMON FUNGUS ON THE BARK OF DEAD TREES. 



Nearly all recently dead trees, and even some that are not yet 

 dead but contain broods of the beetle, are found to have a small, 

 yellow, globular fungus (PL VI) protruding either from the holes in 

 the roof of the egg galleries or those made when the adults emerged 

 from the bark. This fungus, which grows beneath the bark, pushes 

 its way out to develop spores or fruiting parts. 



These fungi are conspicuous objects, and they often occur by hun- 

 dreds on the bark of the trees for two or three years after they have 

 died and the beetles have emerged. The fact that the work of the 

 spruce-destroying beetle seems to make the conditions more favorable 

 for the introduction and subsequent growth of this fungus indicates 

 that it is more closely associated with the work of this beetle than is 

 any of the other bark and wood-infesting fungi of the spruce. It 

 therefore serves as good external evidence that the dead trees on 

 which it is found were killed by the beetle. It will, however, grow 

 from the burrows made by other insects in the bark, or, as observed 

 in one instance, from the burrows of wood-mining beetles, Xyloterus 

 bivittatus Kirby, in wood from which the bark had been removed. 



