74 College of Forestry 
Leptostylus sex-guttatus Say. 
Leptostylus sex-guttatus has been recorded from Canada, 
Massachusetts, New York, New Jersey, Pennsylvania, Dis- 
trict of Columbia, Ohio, Michigan, Wisconsin and New 
Mexico (Leng and Hamilton, 1896, p. 119). Blatchley 
(1910, p. 1072) reports it also from Indiana. Apparently 
little is definitely known regarding the larval host of this 
cerambycid. Beutenmiiller (1896, p. 79) states that it 
“breeds in the wood of locust.” Wickham (1897, p. 152) 
says that it “ may be taken on freshly cut pine,” and Morris 
(1916, p. 197) records having taken a number of specimens 
from a fallen pine. Our record from larch is apparently 
the first time it has been recorded as having actually been 
bred from a conifer. It has also been bred from the limbs 
and trunk of white pine by Mr. A. J. MacNab, a former 
student working in our laboratory. This beetle has been 
found to breed only in the thin-barked parts of the larch and 
the female seems to show a preference for the freshly killed 
or weakened tops or limbs in which to deposit her eggs. 
However, three specimens were also obtained from the trunk 
of a small tree about two inches in diameter which had been 
killed by shading. 
Upon hatching the larva begins to construct its larval 
gallery between the inner bark and sapwood. At first this 
grooves both bark and sapwood to an equal extent, but as the 
larva increases in size a greater per cent of the depth of the 
burrow is excavated from the wood and a less per cent from 
the thin bark, so that when the larva reaches full size about 
nine-tenths of the thickness of the larval mine is in the sap- 
wood. The course of the larva is very tortuous (Fig. 18) 
and is sometimes unusually long for a borer of its size, 
even though it be a two-year form as in the present case. 
In one case where all parts of the larval mine could be readily 
traced it measured 290 mm. to the entrance of the pupal 
chamber. 
At the end of the second season the larva reaches full 
growth, but before pupating it bores into the sapwood, usu- 
ally not more than a half inch from the surface to construct 
