Tech Series 20, Part I, Bureau of Entomology, U. S. Dept. of Agriculture 



Plate XIII. 



Work of Pissodes sitchensis in Bark and Wood of Tops. 



^.— One-yrar terminal. /?.— Four-year-old top: a, One-year internodo; 6, 2-year internode; c, 3-year 

 Internode; d, 4-year internode. (Original.) 



