NOTES ON THE POPULATION ECOLOGY OF CICADAS 
(HOMOPTERA: CICADIDAE) IN THE CUESTA ANGEL 
FOREST RAVINE OF NORTHEASTERN COSTA RICA* 
By Allen M. Young 
Department of Invertebrate Zoology, 
Milwaukee Public Museum 
Milwaukee, Wisconsin 53233 
Introduction 
Several previous field studies of cicadas (Homoptera: Cicadidae) 
in Costa Rica have revealed that different sympatric genera and 
species often exhibit allochronic (seasonal) annual adult emergence 
patterns and habitat associations (Young 1972; 1974; 1975a; 1976; 
1980a, b,c; 1981a,b,c). Most of these studies concerned cicadas 
associated with lowland tropical forest and the Central Valley 
regions of Costa Rica, although one study in particular (Young 
1975) examined some aspects of the population ecology of cicadas 
in a mountain forest. Because different species, and sometimes 
genera, of cicadas are found in different climatic and geographical 
regions of Costa Rica (Young 1976), it is necessary to examine the 
population ecology of these insects in as many of these ecological 
zones as possible. This paper summarizes an ecological survey of the 
cicadas thriving in the steep and very rugged forest ravine known as 
“Cuesta Angel” in the Central Cordillera of northeastern Costa 
Rica. The information reported here complements the studies of 
cicadas in other ecological zones of Costa Rica, although by no 
means does as extensively owing to the difficulties working on the 
very steep slopes of the ravine. It is shown tentatively that (a) the 
cicada fauna of this region includes at least two species not 
discussed or found in the other regions studied, (b) the resident 
species exhibit different annual emergence patterns, and (c) nymphal 
skins of several species are distributed at very low densities and in 
association with various genera and species of leguminous canopy- 
size trees in the ravine habitat. 
* Manuscript received by the editor June 12, 1981 
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