GEOGRAPHICAL DISTRIBUTION. 179 



6.-DISTPJBUTION OF APHIDES. 



"We learn from their fossil remains that Aphides in 

 ancient times were diffused over a large area of the 

 world's surface. Their modern representatives are no 

 less widely scattered. The fact also is interesting that 

 so many well-known species are common to coun- 

 tries widely separated by distance. Thus, out of the 

 185 British species and varieties in this Monograph, 

 the annexed very imperfect table has been drawn up, 

 which shows, subject to the uncertainty attendant on 

 the strict identity of species at such distant parts, the 

 diffusion of these insects over certain areas. 



Aphidinae. England. Germany. Italy. America. 



f Siphonophora 



< Aphis 



(. Other genera 



Lachninse 



Schizoneuringe 



Pemphiginae 



Chermesinaa 



Rhizobiinas 



40 28 15 9 



45 29 20 5 



45 32 28 11 



19 13 11 4 



7 4 4 2 



10 8 6 1 



8 5 11 



11 1 6 



In answer to my inquiries, Mr. J. Monell, of St. 

 Louis, writes that he thinks the most northern 

 American Aphis yet described is Pemphigus tessellatus, 

 Fitch. Hermaphis rhois also occurs far north in 

 Ontario. Perhaps the most southern Aphis of North 

 America is the cotton louse, Aphis gossipii, a published 

 description of which is still wanting. It extends 

 southwards to St. Louis, and eastwards throughout 

 the whole length of the Mississippi valley. Pemphigus 

 vagabundus is common over the greater part of the 

 United States, and is found on the slopes of the 

 mountains of Colorado. 



The Aphis-eating Asaphes is a native of South 

 America ; and the Hemerobiinee and Coccinellidas are 

 also widely spread over that continent. The presence 



