INJURIES BY ROUNDHEADED BORERS. 



351 



like borings fall out, and stopping up the holes with putty or some 

 kind of wax. The dropping of the sawdust-like borings from the 

 logs or timbers always indicates the presence of this or a similar kind 

 of borer. 



THE CEDAR-TREE BORER. 



(Hylotrupes ligneus Fab'.) 



The cedar-tree borer attacks dead and injured Douglas fir, arbor- 

 vita^, red cedar, redwood, western hemlock, Engelmann spruce, juni- 

 per, alpine fir, giant arborvitse, 

 white fir, bigtree, and Arizona 

 cypress. In some cases living, 

 healthy trees may be attacked 

 and killed, and in other cases 

 the death and decay of already 

 unhealthy trees may be hastened 

 by this borer. This species also 

 seriously injures the wood of 

 felled trees for commercial pur- 

 poses and the bark and \vood of 

 those used for rustic work. Its 

 occurrence is general over the 

 United States where its host 

 plants occur. 



The larva (fig. 24, b) is a yel- 

 lowish-white grub about half an 

 inch in length when mature, 

 tapering from the prothoracic 

 segment to the last three ab- 

 dominal segments, which are 

 slightly larger than those imme- 

 diately preceding. The adult 

 (fig. 24, a) is a beetle varying 

 from 7 to 16 mm. in length. 

 The elytra or wing covers are 

 sometimes marked with alter- 

 nate transverse bands of red and 

 black, and sometimes are entirely 

 black or reddish brown. Apparently there is but one generation 

 a year. The egg is laid in crevices of the bark in spring or sum- 

 mer. The larva hatching from the egg excavates a winding, irregu- 

 lar mine in the inner bark, scoring the wood, later entering the 

 sapwood, and sometimes penetrating to the heartwood (fig. 24). 

 ition usually takes place in the sapwood, but sometimes occurs 



FIG. 24. Work of the cedar-tree borer 

 (Hylotrupes ligneus). Section of Ari- 

 zona cypress showing larval mines, a, 

 Adult ; 6, larva. Insects natural size. 

 (Original.) 



