Origin and Diffusion of Blissus leucopterus and Alurgantia histrionica. 151 



vestiges aright, we should, as Mr. Schwarz has previously stated, "look 

 for the true home of the chinch bug near the sea shore," congrega- 

 ting on tufts of grass, both in its early stages and as hibernating 

 adults, where the land is under 1,000 feet elevation, and usually but a 

 few feet above high tide, on an island, peninsula or isthmus, and north 

 of the equator. The soil may be either sand or clay and the surface 

 comparatively level, in occasional areas if not in general, and where 

 the wind will have full play ; and we would expect to meet here 

 other species more or less closely allied to it, and we might further 

 expect it to be able to survive for an unusual length of time in sea 

 water. In neither the Islands of Granada or Cuba, or in Florida do 

 we find species as closely allied to Blissus leucoptei'us as in Mexico, 

 where, according to Uhler's check list, all of the North American spe- 

 cies of the group Blissina occur, except Ischnodemus falicus Say, which 

 Mr. Uhler himself says occurs in Texas, Dakota, Kansas, Louisiana 

 and the United States generally east of the Mississippi basin, speci- 

 mens from the sea coast of Maryland and North Carolina sometimes 

 attain double the size of those found inland, moisture and warmth 

 seeming most favorable to its greatest development. However, even 

 this apparent exception may have had a precisely similar origin, as 

 Ischnodemus prceculalus, a very closely allied species, is found in Guate- 

 mala, and it is not at all improbable that it is from this that /. falicus 

 originally sprung and spread northward into North America. Blissus 

 leucopterus is the sole member of the genus in Central or North Amer- 

 ica, so far as now known, which of itself would lead us to look toward 

 South America for closer relatives. On the Island of Granada, one 

 of the Lesser Antilles, not far distant from the coast of Venezuela, it 

 is reported as being of a larger size and more variable in color, indi- 

 cating a longer residence than in North America. It has not been 

 found on any of the islands between Granada and Cuba, and if this 

 was its pathway to the coast of Florida, it will be observed that both 

 the trade winds and the current would drive them westward instead of 

 northward, so that its occurrence on these islands was possibly brought 

 about by two distinct introductions, one from the south the other from 

 the west or north, most likely the former. We know of its occur- 

 rence in Panama, across which the trade winds blow unobstructed, 

 the elevation being in some places less than 2,000 feet so that it might 

 here become distributed along both the eastern and western coasts 

 and work along both to the northward. Along the west coast it has 



