310 THE PRACTICAL APPLICATION OF ECOLOGY 



5. The Brown Locust (Locustana pardalina Walk.). 



Phasis gregaria = pardalina Walk. 



Phasis solitaria = solitaria Uv. 

 This insect is the chief destructive locust of South Africa, 

 where its swarms have been recorded at various times since 1653. 

 It has been studied in both the laboratory and the field by Faure 

 (1932), who found that the behaviour of the insect in the solitary 

 phase exhibits many of the phenomena also found in L. migratoria. 

 The nymphs exhibit similar colour adaptations to their environ- 

 ment and, likewise, green forms appear as the result of humid 

 conditions. Important breeding grounds are located in the 

 Karoo and in South- West Africa. 



6. The Red Locust (Nomodacris septemfasciata Serv.). 



Phasis gregaria = septemfasciata Serv. 



Phasis solitaria = coangustata Luc. 

 The range of this locust includes the whole of South Africa, 

 together with the Southern Sudan and Abyssinia. In its solitary 

 phase only it is also known from Madagascar, Reunion and the 

 Comoro Islands. Two of its important breeding grounds are in 

 parts of Tanganyika and Northern Rhodesia, while the southern 

 shore of Lake Chad, along with other areas, are regarded as being 

 potential centres for swarm development. 



7. The Rocky Mountain Locust (Melanoplus mexicanus Sauss.). 



Phasis gregaria = spretus Walsh. 



Phasis solitaria = atlanis Riley. 

 There is strong reason to suspect that the common North 

 American grasshopper Melanoplus (atlanis) mexicanus has an 

 intimate relation with the well-known but now extinct Rocky 

 Mountain Locust (M. spretus) which was formerly so dreaded a 

 pest in the United States. The differences between the two are 

 relatively small and suggest that spretus was the long winged or 

 gregarious phase of mexicanus. Faure (1933) conducted some 

 experiments in which the solitary form (mexicanus) was 

 transformed into the gregarious form or phase (spretus). There 

 seems in consequence every probability that the transformation of 

 this Acridian from one phase into the other occurs in Nature in the 

 presence of suitable ecological conditions. The disappearance of 



