Insects Bred from American Larch 89 
inward one-half inch and thence either downward or to the 
side about one inch. These chambers had been opened to 
the inner bark, but not through this, and the openings 
through the surface of the sapwood were not large enough 
for passage of beetle. When removed the beetles were quite 
lively and active.” The beetle emerges through a circular 
hole in the bark. Our records of emergence outdoors extend 
from June 5 to August 3, as follows: 1916, June 6, 7, 8, 
13, 15; July 1, 6; August 3; 1917, June 5, 19, and July 12. 
In the Adirondacks the senior author took adults from hem- 
lock wood June 10, 1915, and balsam June 26, 1915. Pupee 
were cut both from spruce and balsam June 27, 1915. Larvee 
were obtained from hemlock June 10 and from spruce June 
27, 1915. Individuals of S. barbatus differ greatly in size, 
specimens we have varying from 6.5 mm. to 18 mm. 
Insects associated with Serroplapus barbatus include the 
scolytids — Dendroctonus simplex, Polygraphus rufipennis, 
Eccoptogaster picew, Crypturgus pusillus; the cerambycids 
— Asemum moestum, Monohammus scutellatus and Phyma- 
todes dimidiatus ; the buprestid — Melanophila fulvoguttata, 
and the two siricids — Urocerus albicornis and Sirex abbotit. 
None of these habitually precede S. barbatus in the wood, 
but occasionally D. simplex and A. moestum may attack the 
tree first. Most often, perhaps, the melandryid is the first 
insect to enter the living tree — entrance for the egg being 
gained through some mechanical injury such as a blaze or 
other abrasion. In weakened trees Serropalpus is likely to 
deposit its eggs at about the same time as A. moestum and 
before any of the other insects listed above. In such cases 
the adults of both of these two-year forms emerge at the 
same time as do those of D. simplex, P. rufipennis, EB. picee, 
P. dimidicatus, U. albicornis and S. abbotii, all of which 
are one-year forms entering the tree a year later. In other 
eases all of the associates listed above enter the tree during 
the same season and the one-year forms will then have been 
_ gone an entire year before the emergence of S. barbatus and 
the other two-year forms — A. moestum, M. scutellatus and 
M. fulvoguttata. 
