In the issue of Psyche for April,1903, I published a paper on the diffusion of insects in North America, in which reference was made in a footnote to the probable trend of diffusion in the Sphingidæ, and this may be looked upon as supplementary to that publication. In the former paper I could not deal with this phase of the problem of diffusion of insects, to the extent that this family deserves, nor am I certain that this is possible even now, but it seems desirable to point out some suggestive features of the present distribution and probabale diffusion of this interesting family of moths.