1975 ] Robinson and Pratt — Phenology of Hexacentrus 323 
the same climatic regime.) Fulton’s (1951) data for 19 species of 
North American orthopterans show that most of these sing at some 
stage during the period June to November. 
If largish insects such as H. mundus exist on a year-round basis, 
as secondary consumers, it is possible that primary consumers may 
be similarly (relatively) aseasonal. Sustained coexistence (Robinson, 
Lubin & Robinson, 1974: 158) of organisms over long periods of the 
year may be a situation with a high potential for generating species 
diversity. Thus, at the simplest level, it is possible to visualize the 
evolution of a predator specializing in large orthopterans only in a 
situation where, as at Wau, large orthopterans are present on a 
year-round basis. 
Acknowledgments 
The work was carried out at Wau Ecology Institute, which sup- 
ported T.P. in part. We are grateful to Dr. J. L Gressitt for use 
of the facilities at Wau. Donald Windsor prepared the sonagram. 
References 
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