The importance of small mammals as natural control factors for forest insect pests has been indicated by several investigators, particularly by Hewitt (8) and Graham (5) with respect to the larch sawfly, Pristiphora erichsoni Htg. and by Sim (9) with respect to the Japanese beetle, Popillia japonica Newm.

The spring of 1941 in the Ottawa region, being continuously warm and dry, was very favorable for early species of Lepidoptera. Filmata Pears., usually a great rarity, was taken in considerable numbers in a spruce grove, adjacent to a cedar swamp, about 10 miles southwest of Ottawa.

While collecting in Nevada during the summer of 1935 in the Toiyabe Range of Mountains, which rise to an elevation of almost 12,000 feet, and the southern end of which is approximately 75 miles north of Tonopah, I came across a colony of butterflies that have ever since caused me much speculation. From this colony and from another in the nearby Toquima Range, just across the Big Smokey Valley, I secured forty-seven specimens all of which are similar to one another but distinctly different from any other satyrid that I have encountered.

The preceding part under this general title was published in 1941 (Can. Ent., 73: 206-213). In the present instalment, I am discussing species included in extensive series of these flies taken by Mr. H. Elliott McClure at Fort Churchill, Manitoba; by Dr. Mont A. Cazier in California and Nevada; by Mr. and Mrs. John L. Sperry in Montana, Wyoming and New Mexico; by Dr. and Mrs. Henry K. Townes in Washington; and by Mr. John W. Zukel in Idaho.

During the past two summers, we have captured and reared a species of Pseudexentera Heinr. which was breeding in large numbers on the wild apple trees of the Ottawa district. It was also commonly noticed flying around the hawthorn (Crataegus sp.) of this area, and while it was not reared from this plant it is probable that Crataegus is another food-plant.