20 MISC. PUBLICATION 417, U. S. DEPT. OF AGRICULTURE 
little stronger, punctures moderate on disk, smaller on sides and declivity, mod- 
erately close; interspaces approximately equal in width to striae, weakly convex 
on disk, more strongly so on declivity, finely rugose-punctate, becoming uniseri- 
ately granulate on declivity ; ninth interspace not more strongly convex; vestiture 
of disk consisting of short, fine hairs, longer, coarser, and more abundant on 
declivity, but not scalelike. Last abdominal sternite broadly rounded behind, 
strongly convex, moderately closely and roughly punctured, with fine, short hairs. 
Male, cotype.—NSimilar, but with the vestiture of elytral declivity mostly flat- 
tened and scalelike; last sternite distinctly grooved, with the hairs here more 
numerous and longer, parted in middle and directed obliquely backward. 
Remarks —Leconte’s series of gracilis in the Museum of Compara- 
tive Zoology, Harvard University, consists of six specimens in all, the 
first two being designated as “types.” These cotypes are from “Taho 
Valley, Cal.” No. 1, a female, and No. 2. a male, were used in pre- 
paring the foregoing descriptions. 
Hylastes gracilis is a very widely distributed species, for the writer 
has studied specimens from California, Oregon, Washington, Idaho, 
South Dakota, Colorado, New Mexico, Arizona, and Indiana. It is 
possible that the specimens from Lafayette, Ind., were imported in 
western lumber. Host records furnished by D. De Leon from field 
notes are Pinus lambertiana Dougl., P. ponderosa Laws., P. edulis 
Engelm., and “white fir” (Abzes concolor Lindl. and Gord.). Most 
of the specimens were taken in flight, feeding on slabs about a saw- 
mill, or on the surface of logs. - 
This species is an extremely variable one. Specimens chosen from 
series taken at various localities in the rather wide range of the 
group differ somewhat from the type. If considered by themselves, 
these might well be classed as distinct species. However, any series 
of 10 or more specimens from any locality shows a considerable portion 
of the range of variation shown by the entire collection from all 
localities. A short series of 7 specimens from the Lake Tahoe-Pla- 
cerville district of California shows the same tendency. A series of 
3 specimens from Lafayette, Ind., differs from the type scarcely more 
than do some specimens taken only a few miles from the type locality 
near Lake Tahoe. 
The variations shown by gracilis have to do with the size of the 
body and the shape of the pronotum and, to a lesser degree, of the 
elytra, and with differences in the sculpture of the frons, pronotum, and 
elytra. The length ranges from 3.4 to 4.5 mm. In the type the pro- 
notum is widest in front of the middle, but specimens from the type 
locality and elsewhere may be widest near the base with the sides 
evenly, very gently, arcuately narrowed to the anterior margin. Va- 
riations in the elytral shape have to do principally with the shape 
of the apical third. Variations in sculpture are shown as differences 
in the degree of development rather than in the presence or absence 
of certain structures. 
The greatest variations are shown in series of specimens from New 
Mexico and Arizona. Specimens from this region have been studied 
which measure up to 4.5 mm. in length, with the punctures somewhat 
coarser throughout, the median line of pronotum wider, the elytral 
striae deeper, and the discal interspaces more convex and more 
strongly rugose. These specimens seem to agree very well with the 
rather general description of vastans Chapuis, but they occur in series 
that contain not only typical specimens of gracilis but also specimens 
showing all gradations between the two extremes. 
