Insects Bred from American Larch 31 
- M. nigripes Loew. has been previously recorded by Hopkins 
(1899, p. 450) as a parasitic enemy of the larve of 
P. rufipennis. 
Other boring insects which oviposit in the lower trunk of 
the larch either while it is dying or during the first summer 
after death, include the cerambycids Asemum moestum, 
Monohammus scutellatus, Phymatodes dimidiatus, and Lep- 
tostylus sea-guttatus; the buprestid Melanophila fulvogut- 
tata; the melandryid Serropalpus barbatus, and the two 
siricids Urocerus albicornis and Sirex abbotu. Of these, 
Asemum moestum and Phymatodes dimidiatus seem to be 
the only forms which were bred exclusively from the lower 
trunk. A. moestuwm is a sapwood borer and was found only 
in the lowermost few feet of the lower trunk. The eggs are 
often laid in trees which are merely weakened and without 
a doubt the work of the numerous larvae in the bark and 
sapwood greatly hastens the death of the tree. However, 
oviposition may also occur in recently killed trees, and as the 
insects require at least two years to develop, the adults are 
often bred from trees dead two years or slightly more. 
Phymatodes dimidiatus, the other cerambycid, which was 
found to breed only in the lower trunk of larch, is more 
_ typically a dead tree form. Eggs may be laid either in trees 
recently killed or in those dead as much as a year. The life 
history requires a single year for its completion and the 
larvae burrows in the inner bark until it- reaches full growth. 
This species may be associated with A. moestum then during 
either the first or second year of the latter’s life cycle. 
Monohammus scutellatus, Leptostylus sex-guttatus, and 
Melanophila fulvoguttata are three forms which may breed 
not only in the lower trunk but also in other regions of the ° 
tree. All three are two-year forms, the larvae of which feed 
in the inner bark and sapwood, and which enter the wood 
only when preparing to hibernate or to pupate. M. scutel- 
latus and M. fulvoguttata are characteristically trunk 
inhabiting forms, but on occasion do breed in the tops or 
limbs of trees. Indeed, more specimens of the latter were 
obtained from limbs than from the trunk. Leptostylus sex- 
