MIGRATION AND DISPERSAL OF INSECTS : LEPIDOPTERA. 199 



boat between the city and Moultrieville, on Sullivan's Island, at the 

 entrance of the harbour, a summer resort of the inhabitants of our 

 city. The distance is between four and five miles, and when about 

 half-way, or perhaps two-thirds, the steamer passed through an 

 immense stream of butterflies crossing the harbour towards the south- 

 west. They were all of the genus Callidryas. The wind was light, 

 and from the rapid motion of the vessel it was difficult to say whether 

 the insects were aided or opposed by it in their transit. As the vessel 

 passed obliquely through the stream their rate of motion could not be 

 determined, and the dimensions of the stream only roughly estimated ; 

 it seemed to be six or eight yards wide, about as many high, and 

 extended a hundred yards or more on each side of the vessel. Whence 

 they came or Avhither they went could not be ascertained ; they seemed 

 to be crossing the harbour in a direction nearly parallel to the general 

 trend of the coast." Hamilton writes from the New Jersey coast {loc. cit., 

 xvii., p. liOl), some distance further south : " Specimens were observed on 

 the wing nearly every day along the margin of the ocean, flying apparently 

 at the height of fifteen or twenty feet, and about the same distance 

 from the shore, so that their capture could not be eftected, though I 

 took a crippled one, and thus ascertained the species. All appeared to 

 be southward bound, flying steadily but slowly " ; whilst Clark observes 

 {Rand. Xoti's Xat. flist., i., p. b) that, in 1869 or 1870, at Narragansett 

 Pier, the northernmost point at which ('. enbnle has been found, this 

 species "was swarming about the brilliant cardinal flowers, which 

 grew in abundance, and that their numbers were constantly augmented 

 by new arrivals, which all appeared to come from the south. 

 Most of the specimens were considerably mutilated, and apj)eared 

 to have been on the wing for a considerable time ; some two dozen 

 fair specimens, however, were obtained, and some nearly perfect. 

 They were common about the place for several days, and then 

 gradually disappeared." Scudder observes that this butterfly is 

 very abundant in the southern United States, and extends north- 

 wards into the more northern states, and goes so far as to say 

 that its occurrence in the latter is probably entirely due to annual 

 migration. The migrating flocks seen in the southern states are 

 autumnal, and are apparently always in a southerly direction. Davis 

 reports {Insect Life, iii., pp. 835-6) that, in early September, 1890, 

 CalUdnjas ettbnle was flying over the Fayette district of Alabama in 

 millions, from a north-westerly direction, and taking a south-easterly 

 course. When they came to trees or houses they rose gradually and 

 flew over them, and they rested but for a short time on leaves and flowers, 

 and then hastened onward. Writing of the Callidryads observed in the 

 neighbourhood of Obydos, on the Lower Amazons, Bates observes 

 {Xaturalist on the Amazons, p. 181) : " These Callidri/ades seem to be 

 migratory insects, and have large powers of dissemination. During the 

 last two days of our voyage the great numbers constantly passing over 

 the river attracted the attention of every one on board. They all 

 crossed in one direction, namely, from north to south, and the 

 processions were uninterrupted from an early hour in the morning 

 until sunset. The migrating hordes, as far as I could ascertain, are 

 composed only of males, and on this account I do not believe their 

 wanderings extend very far." 



Records of the migration of African butterflies are very rare, and 



