If we watch the many kinds of bees which visit the flowers of Crater Lake National Park, we will sooner or later see a very busy little bee about a half-inch long with its abdomen stuck up at right angles to the remainder of its body. On the exposed surface of the abdomen will be seen a bright yellow mass of pollen embedded in the bristles. This is one of the leaf cutting bees (Megachile), if she is gray color. If she is bright green or blue, she is an Osmia. Both are common in the park. The family of bees to which both of these belong are of special interest, because of their habit of carrying pollen on the abdomen rather than on the legs as do most other bees.