460 EXPEEIMENT STATION RECORD. 



to tlie destructive cliaracters and habits of the described species, and especially 

 because of the number of undescribed species which have not been recognized or 

 have been wrongly identified." Historical references are followed by a consider- 

 ation of the taxonomy of this class of beetles, a revised classification being pre- 

 sented with tables for the separation of the genera. The anatomical details 

 of the adult, larva, and pupa are considered in connection with numerous 

 illustrations. 



" The host trees of Plssodes are, so far as known, restricted to the conifers, 

 and include Pinus, Picea, Abies, Larix, Pseudotsuga, and Cedrus. 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 living terminals and upper 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 saplings and poles. 



"The eggs are deposited in cavities excavated by means of the beak in the 

 outer or inner portion of the inner bark. Some species deposit one or two eggs 

 in a single cavity, while others deposit many. The larvae obtain theiii food 

 from the inner bark through which they extend their irregular mines and when 

 they have completed their development they excavate transformation cells, or 

 pupal cases, in the outer portion of the wood, or, rax'ely, in the inner bark. 

 These cells are enclosed by a thick covering of excelsior-like wood fiber, forming 

 the so-called ' chip cocoons,' which are perhaps a more characteristic feature 

 of the species of this genus than of any other. 



" The characteristic features in the life history of the species are the long 

 life of the adult, the slow sexual maturity, the long period in which eggs may 

 be deposited by a single female, and a single generation annually. In some 

 species the broods develop within two or three months after the eggs are de- 

 posited, while in others it requires a longer period. The adults of some of the 

 species emerge from the bark and hibernate in the ground, while others pass 

 the winter in the bark. 



" The genus is represented in all sections of the United States characterized 

 by natural growth of their host trees, and in other sections where such trees 

 have been introduced to a sufficient extent to support them." 



In a key and synopses of the adult, pupal, and larval characters which fol- 

 low, an attempt is made toward a natural classification of the species of Pissodes 

 into primary and secondary divisions, sections, series, etc., according to char- 

 acters which indicate lines of specialization and natural affinities. Forty-two 

 species are recognized as belonging to the genus, 30 of which occur in North 

 America, 23 of these being described as new to science. The species described 

 as new are : P. similis, from Maine, New Hampshire, and North Carolina, on 

 Abies balsamea and A. fraseri; P. utahensis from British Columbia and Utah 

 and P. harberi from California, Oregon, and Washington, their hosts not being 

 known, but probably Picea ; P. sitchensis from Oregon and Washington on 

 Pieca sitchensis; P. engelmanni from Colorado, Idaho, and Montana on Picea 

 engehnwnni; P. ajyproximatus, occurring from Maine and Canada south to 

 North Carolina on Pinus strobus, P. rigida, P. echinata, M. resinosa, P. vir- 

 giniana, and P. pungens; P. schwarzi, occurring from Alberta, Canada, south to 

 Colorado on Pinus pmiderosa scopulorum; P. canadensis from Manitoba, host 

 tree not known but evidently pine; P. deodarw from Georgia on Cedrus deodara; 

 P. californicus from the Yosemite Valley, Cal., on Pinus ponderosa; P. yosemite 

 from California and Washington on Pinus ponderosa and P. lambertiana ; P. 

 tvebbi from Arizona and New Mexico on Pinus strobiformis, P. scopulorum, and 

 P. murruiinna (contoria) ; P. radiatae from California and Washington on 

 Pinus radiata and P, sylvestris; P. flskei from New Hampshire on Picea rubens 



