4 
taken on May 10, while it was flying in the sun in a field near the forest. 
No adults were found in the cages or collected after May 10, which 
would indicate that in this locality the adults emerge during the last of 
April and the first of May. Specimens of the fly were sent to Mr. D. W. 
Coquillett, who identified them as Cheilosia alaskensis Hunter. 
The last examination of the field breeding cages was made on Octo- 
ber 10. A number of the resin masses that were caged in October, 19038, 
still contained larvee. This would indicate that the insect lives several 
years in the larval state. The fact that larvee of various sizes were 




























































iy Weg 
mi g 











Fia. 4.—Hemlock bark maggot (Cheilosia alaskensis): m, Resin mass with exit hole, adult fly hav- 
ing emerged; 7, longitudinal seetion of similar mass, showing wound in inner bark and outer 
sapwood, pupal chamber and exit hole in outer piteh mass, and original beetle entrance con- 
necting them; o, healing wound in inner bark beneath mass like m; p, healing wound in outer 
sapwood beneath mass like m; q, longitudinal section of wound p; r, maggot; s, puparium; ¢, 
pupa; uw, adult, male; », head of female—all about twice natural size; w, larval head—enlarged 
about 20 times; 2, antenna—enlarged about 45 times (original). 
found at all times of the year and adults only in the spring strengthens 
this belief. 
LIFE HISTORY AND HABITS OF THE HEMLOCK BARK MAGGOT. 
The female fly was not observed ovipositing, nor was the egg found, 
but young larvee were collected from the barkbeetle wounds. It there- 
