strips, and punching holes for tacks in the tips of the strips (fig. 2). 
This was found to be admirably adapted to the work; it was durable, 
could be readily fitted to any surface, and was easily examined by 
simply removing the lid. 
The investigations were started 
too late in the season to secure the 
pup or adults, but many larvee in 
various stages of development were 
collected and studied, and a num- 
ber of the infested wounds were 
covered with the tin cages. 
The most important result of the 
first season’s work was the discovery 
that the primary cause of the attack 
and subsequent injury by the bark 
maggot was the work of the hem- 
lock barkbeetle (Hylesinus n. sp.) 
(fig. 8, a)! which was found exca- 
vating short burrows (fig. 3, b,¢) in 
the healthy bark, and through it 
to the surface of the wood, where 
a small wound was made, causing 
a slight flow of resin (fig. 3, f). 
These burrows were evidently made 
by the beetles for the purpose of 
obtaining food, and not for the 
purpose of depositing eggs, since 
neither eggs nor larvee of the beetle 
were found, and the burrows were 
soon abandoned. Some of these 
food burrows were healed over with- 
out further injury to the wood, 
while others were open and con- 
tained a small amount of resin. 
These abandoned galleries, with the 
resin, formed ideal places for the 
young bark maggots to begin their 
work, and were, apparently, utilized 
in preference to any other wounds. 
The investigations of 1904 were 
more successful. Upon the first 




































































Fra. 3.—Development of the black check in west- 
ern hemlock: a, the beetle (Hylesinus n. sp.) 
that makes the primary injury—natural size: b, 
entrance of beetle in outer bark ; ¢, longitudinal 
section of a similar entrance: d, 
showing wound in inner bark; e, same, showing 
wound in outer sapwood; f, resin exuding from 
an entrance after beetle has gone: g, fresh resin 
mass on outer bark, indicating hemlock bark 
maggot at work; h, longitudinal section of simi- 
lar mass, showing position of maggot: i, maggot 
wound ininner bark; j,same, in outer sapwood: 
k, resin mass after maggot work is done and 
the pupa is formed; J, longitudinal section of 
similar mass, showing pupa, the wound begin- 
ning to heal (original). 
same as }b, 
examination of the breeding cages on April 27 one adult male was found. 
On April 30 a female emerged, and May 8 two males were secured from 
resin masses placed in cages in the laboratory. Another female was 

‘Bul. No. 48, Div. Entom., U. 8. Dep. Agric., p 20. 
