2G 



MISCELLANEOUS FOREST INSECTS. 



some species there are alternating smaller, less regular spines between 

 the dorsal and lateral ones. The lateral area of each tergite is armed 

 with two spines and the epipleural lobes are each also distinctly or 

 obscurely armetl with one or two spines, and the ninth segment, as 

 usual, is armed with two prominent pleural sj)ines. (See Hopkins, 

 1909, figs. 37, 38, for anatomical nomenclature.) 



HOST TREES. 



The host trees of Pissodes are, so far as known, restricted to the 



conifers, and include 

 Pinus, Picea, Abies, 

 Larix, Pseudotsuga, 

 and Gedrus. Some of 

 the species infest both 

 living and dying or 

 newly felled trees, 

 while others appear to 

 confine their attack to 

 those which are sickly, 

 dying, or felled. Some 

 of them infest the liv- 

 ing terminals and up- 

 per branches, others 

 the upper or middle, 

 stem, or base; some 

 prefer to infest the 

 thick bark of large 

 trees , while others 

 show a preference for 

 the thinner bark of sap- 

 lings and poles. (See 

 table, pp. 41-42. )» 



GENERAL HABITS. 



The eggs are depos- 

 ited in cavities exca- 

 vated by means of the 

 beak in the outer or 

 inner portion of the 

 inner bark. Some spe- 

 cies deposit one or two 

 eggs in a single cavity, 

 while others deposit many. The larvae obtain their food from the 

 inner bark through which they extend their irregular mines (Plates 

 XII to XVIII), and when they have completed their development 



Fig. 8. -^ ; Pissodas pi peri, front of hoail of lar\a. 6, Frontal suturo; 

 c, subdorsal stripe; d, median line; e, epicranial sutuic; /", apical 

 papilla; g, labial bristles; h, clypeal bristles; i, labral hooks or 

 epipharyngeal bracons; J, epipharyngeal papilla; k, oesophagus. 

 B: Pissodes nemorensis, front of head of larva. Nomenclature 

 same as in A. (Original.) 



