LAWSON : KANSAS CICADELLID^. 31 



That leaf hoppers, however, are able to push out the limits 

 of their environment once they are in a country and unhindered 

 by high mountains or climatic conditions essentially different 

 from that to which they are adapted, is very evident. The 

 range of many of our North American species is steadily being 

 increased. Thus Professor Osborn shows that Drxculacephala 

 reticulata seems to be steadily pushing northward from its 

 southern home, seemingly having the power to adapt itself to 

 such minor changes as it may meet. Euscelis exitiosus he also 

 believes to have recently spread over the United States. 



In the United States we find a rather general distribution of 

 the members of this family with the exception of the Paropinse. 

 The members of this subfamily are seemingly confined to Cali- 

 fornia or at least to the west of the Rockies. The Biftliosco- 

 pinse on the other hand, are found well across the states The 

 Agallia group while found from north to south and east to west, 

 is yet undoubtedly subtropical. The genus Idiocerus is in the 

 main more northerly in its distribution. The members of .he 

 genus Macropsis are more abundant in the Northeastern states, 

 few reaching the Pacific coast. Oncopsis is practically north- 

 ern in its distribution, while the members of the genus BijtJio- 

 scopus are well represented in the Western states though also 

 occurring in the south and east. Thus in one subfamily we 

 find groups which favor each of the several portions of the 

 country in their distribution. 



The Cicadellinse are tropical or subtropical as a group. • Nat- 

 urally we therefore find the subfamily best represented in our 

 Southern states though many species seem to have been able 

 to adapt themselves to northern conditions and some are found 

 commonly even in Canada. They occur across the continent 

 from east to west. Only two or three of the nearly fifty species 

 of the United States are known to occur in Europe. Many 

 of them, however, are found in Mexico and the West Indies, 

 some such region seemingly being their original home. 



Comparatively few members of the subfamily Gyponinse seem 

 to be found on our western coast. As a group they seem to 

 be tropical or subtropical and hence are best represented in 

 our Southern states, though some species extend through our 

 Northern states into Canada. They are found in the Eastern 

 as well as the Western states. 



