Apparently there has been scarcely any published study of the egg-laying or other habits of the adult _Oedemagena_ in relation to _Rangifer arcticus arcticus_, other than a few recent notes by Banfield (1951a: 31-32, fig. 17); but its behavior in relation to the Lapland Reindeer seems to be fairly well known, and it is summarized by Jacobi (1931: 245-246). In the case of the Reindeer, the fly's eggs are laid (during the summer) generally on the legs, belly, and tail region of the victim; the larvae, on hatching, bore through the skin, travel widely through the body, and finally (in the autumn) reach the place for further development--beneath the skin of the back on both sides of the vertebral column. Each one makes a breathing-hole through the skin, and uses this as an exit when leaving the host in the following June. Only the younger animals, from one to about four or five years old, are heavily infested; those still older are spared, possibly having learned to guard themselves better against the fly. Curiously enough, the fawns are said to escape this parasitism entirely.
My own observations on the larvae were restricted to a few Caribou specimens in June and in the autumn. As with the Reindeer, the Caribou fawns in their first autumn showed no visible infestation, as I noted in looking over some fresh hides on September 10, and as was noted again in a fawn of September 26. Fred Schweder, Jr., made the remark that larvae would be evident in the fawns by the following spring; this may indicate that the larvae have not, in the autumn, completed their journey to their final position on the Caribou's back. I learned of no immunity on the part of old adults.
Fullgrown larvae still remained in bucks secured on June 3 (fig. 17) and 18. According to Charles Schweder, they drop out in June. In the buck of June 3 there were perhaps several dozen warbles, each surrounded by a mass of repulsive tissue; in another buck of June 18, there were apparently more than 75. "It may be assumed," says Johansen (1921: 24), "that the pupae lie on the ground for about a month before the flies appear." He found (1921: 29) the adult flies abroad at Dolphin and Union Strait by July 14.
In a buck of August 17 the new warbles (or perhaps merely warble scars from the previous June--_cf._ Banfield, 1951a: 32) on the inside of the skin were not very numerous. Some were medium-sized, but most were so small that it was not deemed necessary to scrape them off; they had comparatively little fatty tissue about them and were merely allowed to dry up. The number of warbles (or warble scars) found in autumn specimens varied considerably, up to a maximum of roughly 200. They were situated mostly along the mid-dorsum, and more on the lower back or rump than farther forward. The number appeared to be approximately 130 in the skin of an adult doe that was nailed to the log wall of a cabin for drying on September 15 (fig. 18). A doe of September 21 seemed to have less than the usual number of warbles.