The Boundary Hill Research Reserve is an area approximately twenty-five square miles in extent which has been set aside by the administration of the Yosemite National Park for the study of wild life in the primitive state. The reserve takes its name from Boundary Hill, the only prominence designated on the topographical maps of the U. S. Geological Survey as included within its limits. On the south it is bounded by the north rim of Yosemite Valley, on the east by Yosemite Creek, on the north by the Tioga Road, and on the west by Cascade Creek. It was the privilege of Air. Fred Ziesenhenne and myself, as members of the Yosemite School of Field Natural History, to spend five days, July 14 to 18, 1933, inclusive, collecting butterflies as our contribution to a general survey conducted by the twenty members of the class under the direction of Mr. Joseph Dixon, Field Naturalist, National Park Service. <br /><br />While it is realized that relatively little may be accomplished in five days by two collectors, no matter how energetic, it is the belief of the writer that the evidence obtained is worthy of recording as a basis for a later and more detailed study. Arriving as we did at the height of the season we were able to take over forty species of diurnal Lepidoptera, including several not heretofore recorded for the Yosemite region, as well as larvae and pupae of several more.