Plate III. 
Fie. 6. Another section of trunk of larch tree showing 
the work of woodpeckers in removing the outer bark in order 
to feed upon the borers therein. In this case the work has 
not been quite so thorough as in Fig. 5. Reduced to about 
two-fifths natural size. 
Fic. 7. General view of the engravings of Hccoptogaster 
picee upon the surface of the wood of larch tops, showing 
the general appearance of larch wood one year after it has 
been attacked. This section of the tree contained nearly a 
pure culture of FH. picew, but one engraving of P. rufipennis 
may be seen near the lower left-hand corner of the photo- 
graph. Note the different types of burrows. Reduced to 
slightly less than two-fifths natural size. 
Fig. 8. Engraving of 2. picew in larch, showing the bur- 
row with two egg-galleries, which is the most common type. 
Note that there is a much larger number of egg niches in 
the upper egg-gallery, although in this case the two are about 
the same length. Typically the upper egg-gallery, which is 
the first one begun, is both longer and contains more egg 
niches. The larval mines at first are nearly parallel to each 
other and at nearly right angles to the egg-gallery, but later 
they become very tortuous. The wider, deeper, more tortuous 
burrows (as those in the upper left-hand region of the pic- 
ture), which appear whiter on account of their grooving the 
sapwood so deeply, are made by the young adults, which feed 
in the old host for a time before emerging. About four-fifths 
natural size. 
Fie. 9. Engraving of 2. picew with three egg-galleries. 
About four-fifths natural size. 
