I also purchased five large trees of a coarse variety of Poplar, known here as Cottonwood, that were to be cut down, as they had commenced dying, “caused by a _grub_ working in them.” I found it to be a _Cossus_ larva, but not as large as that working in the Oaks. Judging from a comparison of the empty pupæ cases found in them, which in these Poplars were very numerous, it is not the one described by Mr. Bailey in last January number as “_Cossus centerensis_” but seems more like _Xystus robiniæ_. I had three of the trees cut down in order to obtain the pupæ; judge of my surprise and disappointment when my man came in, telling me he could find _none_ but “lots of nasty _grubs_, of which he had given the near chickens probably a hundred or more,” not thinking them valuable to me. I sent him back with instructions to preserve every larva he could find, and I now have about fifty in every stage of development from the half-inch beet red, the nearly two-inch long pink, to the about two and a half-inch long greenish-white larva. I have some in the wood in their own burrows, and have put the rest in sawdust; and I have ordered him to cut me pieces of that wood, bore some holes in the ends and put in the other larvæ, and cork it in, leaving a few air-holes; with these I hope to complete my observations in a warm room. I did not know before that these hybernated in the larval state, much less did I think they would be found of different moults. A. H. MUNDT, Fairbury, Ills. MIGRATION OF BUTTERFLIES. DEAR SIR,— I have received the following notes on migration of certain butterflies from Prof. J. E. Willet, of Macon, Ga., dated 19th Jan’y, 1880. W. H. EDWARDS, Coalburgh, W. Va. “I saw Callidryas _Eubule_ passing here in great numbers during Sept., Oct. and Nov., 1878, from N. W. to S. E. About noon, when they were most abundant, there would be half a dozen visible all the time, crossing a 15-acre square of the city. They pursued an undeviating course, flying over and not around houses and other obstructions. They flew near the ground, and stopped occasionally to sip at conspicuous flowers. A geranium with scarlet flowers, and set in the open yard, attracted most that flew near it. Papers in Southern Georgia noticed the great numbers passing at different points; and a friend in Southern Alabama sent me specimens of the same, saying that they were subjects of speculation there. About March, 1879, there was a similar migration from S. E. to N. W., but in diminished numbers. I saw the fall migrations again Oct. and Nov., 1879, but in smaller numbers than in 1878. A lady of So. Georgia told me that her husband called her attention to the fall migration 26 years ago, and that she had observed it every year since. C. _Eubule_ is found here in small numbers at other seasons of the year.” EARLY STAGES OF EPHEMERIDÆ.