Certain of the nesting habits of the wasp, Sphex xanthopterus (Cam.), have been observed at and near Los Angeles, California. The insect nests for the most part in the moist or wet, sandy soil of the river bed. It digs a short tunnel and enlarges it into a cell at the end. Into this is stored a stung lepidopterous larva, often the young of the moth, Zale lunata (Drury) and its varieties, to the side of which is fastened the egg of the wasp. The entrance to the tunnel and nest is then closed and in due time, if all goes well the egg hatches, the larva devours the prey, spins its cocoon, pupates, and later emerges an adult wasp. A more detailed account of some of the facts in its nesting habits and life history is given below.

During the summer of 1930, I returned to the north shore of the Gulf of the St. Lawrence and spent three months collecting there. Most of the collecting was done at Thunder River, a village on the mainland opposite the western end of Anticosti Island, and at Bradore Bay, situated at the western extremity of the Straits of Belle Isle.

Male. Very similar in all respects to guttata McD. but noticeably larger in size. Thorax deep blackish, tinged with brown in the pleural sutures. Abdomen with segments 2-6 and anterior portion of 7 whitish, hyaline, with considerable brownish shading on 2. In place of the lateral black dots of guttata there is a short black transverse streak in the postero-lateral corner of segments 2-6 with some slight brown suffusion anterior to it, especially on segment 2. Rear segments deep chocolate-brown.

Somewhat similar to C. celeripes Lec, but with fully developed wings. Brownish bronzed, the punctured part on thc elytra greenish white or greenish blue; antennae with four basal joints bronzed, apical joints dark, hairy; palpi pale, yellowish, apical joints dark at tip; elytral markings grayish white, somewhat variable, but usually with a narrow marginal line or dash at middle, an apical line or lunule, the marginal line usually connected with the apical lunule, twelve of the thirty-three specimens have an indication of a humeral lunule and trace of a median spot, suggesting that a median band may be found on some future specimens.