THE CANADIAN ENTOMOLOGIST. 



165 



reality, the edges of the woods are usually, and the interior quite often, 

 where not too dark, the haunting place of these hamadryads where they 

 escape notice for a time, while the moths, which I here especially discuss, 

 are fond of these quieter dusky places in the daytime. 



To understand the way in which our species of North American 

 Moths are distributed (and by North American we mean those inhabiting 

 the territory north of Mexico and the West Indies) we must then study 

 the physical geography of the continent. There are a host of species 

 which for the most part depend on special kinds of plants, and their 

 diffusion is in this way limited by the range of the plants upon which their 

 caterpillars subsist. The botany of a region is, to this extent, an index 

 to its entomology. But, from their greater activity, these flying flowers, 

 the Moths, range on occasion out of the way of the plants upon which 

 they have fed in their young stages. If we take a map giving a bird's-eye 

 view of the continent, with the elevations marked, we can understand the 

 problem better. Ranges of mountains obstruct, valleys and river chan- 

 nels assist the dispersion of Moths. They travel on the wings of the 

 wind, and an important factor in their range is the prevailing seasonal 

 direction of the air-currents. There is, in North America, a summer 

 migration of many species from the South to the North, aided by the 

 prevailing winds, so that, towards the Fall, several tropical kinds have 

 followed for long distances the coast line, or up the valley of the Missis- 

 sippi. The Gotton-worm Moth, which, in its caterpillar state, inflicts great 

 damages upon the plantations, is a case in point. If the direction of the 

 prevailing winds in early summer from South to North were reversed, the 

 Cotton Worm would not come up North. I have noticed that its advent 

 along the coast was retarded by contrary or no strong winds. This seems 

 to be the view held by planters along the coast of Georgia. Individual 

 specimens or flocks of other moths, such as the Great Owlet, N. Agrip- 

 pina, the Blue and Green Hawk, Argeiis Labruscae, visit us yearly, com- 

 ing up from the West Indies, with other of the larger stronger-winged 

 Sphingidse and Noctuidse. They die out in the winter and leave no 

 progeny behind to continue the species the ensuing spring. But many 

 kinds have effectually colonized themselves in South Florida, and there is 

 probably an irregular line of successful hibernation for all these foreigners, 

 including the Cotton-worm Moth, to be drawn through the Southern States. 

 It is, then, clear that the provisions of Nature for the sustenance of these 

 animals render a certain exertion necessary on the part of the Butterflies 



