54 PSYCHE [April 



this side of the Rio Grande up to a few years ago, when it began its depredations 

 in the vicinity of Brownsville, Texas. Among the Hemiptera or true bugs the 

 Chinch-bug and the Harlequin cabbage-bug offer excellent illustrations of the 

 trend of insect diffusion from the southwest.^ 



Diffusion from the Southeast. 

 {Antiliean trend, D, on fnap.) 



Of the remaining entrance gate, that of southern Florida, I will say that there 

 is no doubt that many species have made their way up through the Antilles 

 from South America. The distribution of Calidota strigosa illustrates that fact, and 

 there are many other illustrations ; but as the United States has recently gained 

 such a supremacy in the Greater Antilles, we may confidently look for considerable 

 activity in the study of the insect fauna of these islands, and I would rather not 

 anticipate the results of this work. I believe, however, that we shall find the 

 Central American and Mexican route the more important.^ 



In taking up the introductions by the agency of man, I should like to approach 

 that subject by here calling attention to what appears to have been such an intro- 

 duction of Aphodius lividus,^ which must have become established at a point some- 

 where in the West Indies, from whence it has spread to Florida, and from there 

 pushed its way westward to extreme southern California, entering the state at a 

 point where the mountains are more easily passed through, and started up the 

 Pacific coast. This is a new line of diffusion, and quite a suggestive one as well. 



The Eastern Gateway, and the Diffusion Westward of Species 

 Introduced Through the Agencies of Man. 



{The Transappalachian trend, E^ on ?nap.) 



I have recently discussed this trend of diffusion quite at length^ and it is 

 unnecessary to repeat what I have there stated, except to state that the Appala- 



^ See my paper published in the Journal of the Cincinnati society of natural history, vol. i8, p. 141-155. 



- Probably a majorily of the Sphingidae came by the way of the Antillean trend. Their long, slender, powerful winj;s, 

 like those of sea birds, such as the Albatross and Frigate bird, especially fit them for such a journey. The family is a 

 tropical one and has spread from its ancient home to nearly all countries. That these insects are often obliged to brave 

 the sea is shown by the fact that a Frencli gentleman once showed Dr. Hermann Behr, of San Francisco, a collection of 

 insects caught on shipboard after a heavy gale, fifty-four geographic miles off the coast of Brazil. Every one of the 

 insects were sphinges, belonging to three genera. 



•■".^Iso occurs in Transvaal, South Afiica. 



^Thirty-second Rept. ent. soc.Ont. p. 63-67, igoi. 



