166 The Ohio Journal of Science [Vol. XVI, No. 5, 



they are associated with certain kinds of plants upon which 

 they depend for their sustenance and the abundance of leaf- 

 hoppers will be affected, necessarily, by the abundance of the 

 food plant and its availability as food material. An undue 

 increase of the leafhoppers, which should result in the dim- 

 inution of the food supply, must necessarily affect the possibili- 

 ties of multiplication and cause a certain reduction in the 

 number of the insects. This is by no means the only statement 

 of conditions, as, aside from these two forms which may be 

 associated in the same area, a large number of other organisms, 

 both plant and animal, will affect the problem. The occurrence 

 of different birds and predaceous insects which prey upon the 

 leafhoppers will naturally reduce their numbers and to that 

 extent favor the plants which serve as their food, whereas 

 the presence of herbivorous animals, grasshoppers, cutworms, 

 etc., serves to reduce the available food supply. Aside from 

 these dominant forms, there are also various fungus parasites 

 which attack both insects and plants and which play their 

 part in the complex, of which the leafhoppers are such a con- 

 spicuous element. Furthermore, the minute insect parasites 

 which attack the leafhoppers add their part, tending to keep 

 the latter reduced in numbers." 



Some of the points here mentioned are well borne out in 

 South Africa; thus the increase in vegetation from the west to 

 the east, is followed by a great increase in the numbers of forms, 

 with the result that the Eastern Province and Transkei terri- 

 tories (the Caffraria of Stal), contain a greater number of 

 individuals. It must be emphasized here that but mere 

 passing comment on the ecological relations can be given, 

 as our knowledge of the group precludes any but bare state- 

 ments of recorded observations. The presence in South 

 Africa of a fauna restricted almost entirely to the dry Karroo 

 region, makes the study of ecology an interesting one. Added 

 to this the subtropical character of the climate and vegetation 

 of Natal, and the northern regions, one is confronted with a 

 variety of conditions scarcely paralleled on any other continent. 

 Many of the endemic genera and species are restricted almost 

 entirely to the Karroo region. 



The relations of the higher animals to the Homopterus 

 fauna can only be touched on. While it is known that herbivo- 

 rous animals in foraging, arc likely to swallow the eggs, yet the 



