PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 
SMITHSONIAN INSTITUTION 
U. S. NATIONAL MUSEUM 
Vol. 92 Washington : 1942 No. 3154 
REVISION OF THE GENUS PHLOEOSINUS CHAPUIS 
IN NORTH AMERICA (COLEOPTERA, SCOLYTIDAE) 
By M. W. BiackMAn 
INTRODUCTION 
Tue genus Phloeosinus Chapuis is one of the most widely dis- 
tributed genera of bark beetles, as it occurs in all the large con- 
tinental land masses and in many islands. Although the genus is 
not so large, as regards the total number of recognized species, as 
are several other genera, in North America it appears to be second 
only to Pityophthorus in the number of known species. In the 
present paper, which deals with all North American forms from 
Alaska to Mexico inclusive, 45 species, including 16 previously un- 
described ones, are recognized as valid. Thorough collecting in 
Mexico and Alaska would, without doubt, bring to light additional 
species. 
All but three of the known North American species of PAloeosinus 
breed in the inner bark of cupressine and taxodiine trees of the 
genera Sequoia, Taxodium, Libocedrus, Thuja, Cupressus, Chamae- 
cyparis, and Juniperus. Of the three nonconforming species one 
breeds in Pinus and two in Picea. Although plainly congeneric, 
these three species differ from the others not only in host selection 
but also in certain evident morphological characters that serve as a 
basis of primary separation. 
The breeding habits of the species do not differ greatly from 
those of many other bark beetles. The brood burrows are constructed 
in the inner bark, often grooving the surface of the sapwood rather 
deeply. The burrow usually consists of a simple longitudinal egg 
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