VOLUME 24, NUMBER 2 117 FORBES, W. T. M. 1954. Lepidoptera of New York and Neighboring States. III. Noc­ tuidae. Cornell Unlv. Agri. Exp. St. Memoir 329. FRENCH, G. H. 1880. Notes on Catocala hunting. Canad. Entomol. 12: 241-242. GKOTE, A. R. 1872. On the North American species of Catocala. Trans. Amer. Entomol. Soc. 4: 1-20. 1873. On the genus Catocala. Canad. Entomol. 5: 161- 164. 1876. On species of Catocala. Canad. Entomol. 8: 229-232. HAMPSON, G. F. 1910. Catalogue of the Lepidoptera Phalaenae in the British Mu­ seum. Vol. 9. London. HOLLAND, VV.]. 1903. The Moth Book. New York. (Reprinted 19fi8, with annota­ tions by A. E. Brower) . HULST, G. D. 1880. Remarks upon the genus Catocala with a catalogue of species and accompanying notes. Bull. Brooklyn Entomol. Soc. 3: 2-13. 1884. The genus Catocala. Bull. Brooklyn Entomol. Soc. 7: 13-56. JOHNSON, J. S. 1882. Catocalae taken in the vicinity of Frankford, Pennsylvania. Canad. Entomo!. 14: 59-60. KETTLEWELL, H. B. D. 1958. The importance of thc microenvironment to evolution­ ary trends in the Lepidoptera. Entomologist 91: 214-224. McDuNNOUGH, J. 1938. Checklist of the Lepidoptera of Canada and the United States of America. Part 1. Macrolepidoptera. Mem. Southern Calif. Acad. Sci. Vo!' 1. HOWLEY, R. R. A.'1D L. BERRY. 1909. Notes on the study of some Iowa Catocalae. Entomo!. News 20: 12-18. SARGENT, T. D. AKD R. R. KEIPER. 1969. Behavioral adaptations of cryptic moths. I. Preliminary studies on bark-like species. J. Lepid. Soc. 23: 1-9. COM~1UNAL ROOSTING IN COLlAS AND PI-IOEBIS (PIERIDAE) I-IAIlRY K. CLENCH Carnegie Museum, Pittsborgh, Penna. Two instances of communal roosting in coliadine pierids have recently come to my attention. They have to do with different genera, of consider­ ably different body size, and occurring in different major environments, but there are several striking similarities and I believe a common explana­ tion may satisfy both. Colias eUl'ytherne Boisduval In an open meadow near Pittsburgh, Pennsylvania, at about 5:30 PM, EST, on 18 September 1969, I saw Colias eurytherne in fairly large num­ bers preparing for the night. A few of them were still active, hut most had already sought roosts. The sun was within 15-20° of the true horizon, but was destined to disappear a little prematurely behind a low, tree­ covered hill, and the field was already partly shaded. 118 JOURN AL OF THE LEPIDOPTERISTS' SOCIETY A few eurytheme were down in the dense grass, probably within 6-8 inches of the ground, each some distance from any other. Some, similarly isolated, were low (Jess than a foot above the ground) in dense crown vetch on a steep, still sunlit, west-facing slope that forms the eastern edge of the field. Still others, also alone, were hanging from leaves of isolated emergent forbs, mostly goldenrod, usually within 1-2 feet of the ground. I saw, however, two conspicuous aggregations. Each consisted of 5 males, clinging to the leaves of a clump (2 or 3 stalks) of emergent forbs in the middle of the field, the sun still on them. In each clump the individuals of eurytheme were only an inch or so apart and within a foot or two of the ground. All the individuals I could examine closely enough, both those seen singly and those in the two aggregations, were basking laterally (wings appresscd, the sun irradiating one side ), the only basking posture I have ever seen in Colias. The orientation to the sun was so consistent that the best way to search for them was to keep the sun at my back as I looked: the little patches of sunlit yellow were conspicuous, even though some turned out on closer inspection to be merely yellowed leaves. Phoobis sennae eubule Linnaeus At Horseshoe Beach, Dixie Co., Florida, on 24 November 1969, at about 3:55 PM, EST, I saw an assemblage of Phoebis sennae eubule. In an empty trailer park consisting of bare sandy ground there were a few scattered low trees, mostly Sabal Palm. The trunk of one of these palms was nearly covered with a dense growth of a vine part of which, about six fe et above the ground, was in the form of a hollow pocket about two feet across, facing wcst. In this pocket were 11 sennae (96, 2'l' ). The sun was low and much of the area was already shaded by some nearby buildings, although the sennae were still sunlit. Elsewhere, within a hundred feet or so, several sennae were still actively flying along with many other butterflies. Within the pocket of the vine, however, they were almost all in repose, wings appressed and broadside to the sun in the same lateral basking posture seen in Colia.s. There was one exception. When I ap­ proached the group one of the females had her wings fully outspread and and her abdomen elevated at right angles to the rest of her body and to the plane of her wings. This is known to be a rejection posture, a response to an attending male indicating that she is not receptive to copulation. The rest of the group was quiet, however, and she SOOl1 abandoned the posture and folded her wings together like the others. Some ten or fifteen minutes earlier I had looked briefly at the as­ semblage and had noted only four or five individuals in it. I therefore VOLUME 24, NUMBER 2 119 suspect that the group was slowly being added to by new arrivals. (Pos­ sibly one of these was a male who on arriving had attempted to copulate with the female and had elicited the rejection posture I saw.) The color of sennae eubule is distinctly greenish yellow. The resem­ blance of the color of these individuals to the yellow-green leaves of the vine was so extremely exact that it was difficult to distinguish one from the other, even at close range. Discussion Nearly all the roosting Colias I saw, whether they were single or in the aggregations, were situated more or less close to yellowed or to yellowing leaves, whose color closely matched their own. An association of Co-lias with yellow flowers or leaves has long been known (Scudder 1889, p. 1123; Clark 1932, p. 159). Several times I have noticed a similar association in Phoebis. In a local­ ity in eastern Mexico I once saw them at rest in a low shrub with many yellow leaves. The size and color of these leaves so closely resembled the Phoebis that at a short distance it was impossible to tell which was which. At Chokoloskee, Collier Co., Florida, on 20 November 1969, I watched a Phoebis agarithe maxima Neumoegen in late morning, basking laterally for several minutes on a yellowed leaf of papaya along a path in a patch of low forest. This leaf was many times thc size of the agarithe, but its orange yellow color was so close a match that the butterfly was almost invisible against it. This latter observation is particularly suggestive when taken in conjunction with the sennae already described. These two species are of about the same size but they are conspicuously differently colored: greenish-yellow in sennae, orange-yellow in agarithe. In each instance the background color closely resembled that of the particular species. See also Longstaff (1909, pp. 640-643). Communal roosting is not well-known in either Colia'; or Phoebis. I think that in both genera it is an occasional occurrence only. This assump­ tion is supported in Colias by the fact that at the same time that I saw the aggregations there were many other individuals preparing to roost alone. The above observations suggest the possibility that among the various factors that enter into the choice of a roosting site, the presence nearby of an appropriate shade of yellow is important. This may lead to single roosting individuals, but on the other hand, if the individual itself im­ proves the color match or adds to the conspicuousness of the yellow at the site, then it may attract still others and result in an aggregation. In this sense, then, communal roosting may be simply a by-product of their xan thotropism. 120 JOURNAL OF THE LEPTDOPTEHISTS' SOCIETY Literature Cited CLARK, AUSTIN H. 1932. The butterflies of the District of Columbia and vicinity. U. S. Nat. Mus. Bull. 157. 337 pp. LONGSTAFF, C . B. 1909. Bionomic notcs on butterflies. Trans. Ent. Soc. London (1908). pp. 607- 673. SCUDDER, SAMUEL H. 1889. The butterflies of the eastern United States with special reference to New England. Cambridge, Mass. 3 vols. TWO NEW MEXICAN HESPERIIDAE LEE D. MILLER Thc Allyn Foundation, Suite 712, Sarasota Bank Building, Sarasota, Florida Among the Hesperiidae collected by the Carnegie Museum-Catholic University of America expedition to eastern Mexico in January, 1966, were two short series of ap­ parently new hesperiine skippers. When the Allyn Mexican expedition was under­ taken in January and February, 1969, an opportunity was provided to obtain more specimens and to observe more closely the habits of these hesperiids. The combined series from the two trips comprise the type-series for the two new species below. Although perhaps not so many specimens nor species can be taken in Mexico during the temperate zone winter as might be collected during the summer months, many worthwhile species apparently are found only during January and February, or at least are most abundant during this time. These two new skippers are evidently among such "winter" butterflies. Vinius freemani Miller, new spedes Figs. 1,2 ( i'; ), 3 ( S' ),7 ( ;t; genitalia) Male: Head, thorax and abdomen blackish-brown, clothed above with greenish­ ochre hairs; below with dense tan hairs.