INSECTS AFFECTING FOREST TREES. 



521 



to a considerable distance in a direction nearly parallel with the wood fibers. The 

 egg notches are also seen. This same gallery, eaten in the bark, is represented 

 at plate 14, figure i. It will be seen that in this instance at least the larvae bored in 

 the sap wood rather more than in the bark. 



A still more advanced stage is shown at plate 14, figure 5, which represents 

 a portion of a trunk which had been injured b\- a large number of the beetles. 

 The adult galleries, egg notches and the work of larva; or grubs can all be 

 seen. 



Plate 14, figure 4, represents a portion of a very badly infested trunk after the 

 attack has practically ended. It will be observed that the inner bark is a mass of par- 

 tially decayed tissues filled with numerous larval and adult galleries. Figures 22, 23 



mmmi 



JOUT£L 



FIG. 23. (iALLERIES OF TOMICUS 

 DALSAMEUS. 



SIIOWI.NG I'lTCH CHAMBER, PURAL CELL IM SAP 

 WOUD AND WORK OF YOUNG MoKO- 

 kanttltUS LAKVA. ORIGINAL. 



FIG. .-1 -I'l I 1 TWIG. 

 SHOWING GIRDLING BV ADULT GALLERIES OF 

 Tomicits halsamcus. origin.\l. 



represent the condition after the decayed tissues liave been removed. The adult 

 galleries may be readily recognized where they score the surface of the wood and 

 hei'e anil there are peculiar chambers a little to one side of an adult gallery. These 

 arc not central or entrance chambers but are evidently little cavities hollowed out 

 by the beetles for the reception of balsam and show conclusively that the tree must 

 have been alive at the time of the initial attack. Hard, dried balsam can easily be 

 found in such cavities. 



Figure 24 illustrates very nicely how thoroughly this insect may girdle twigs. It 



