1980] 
Young — Ecology of Cicadas 
191 
genera and about ten species of cicadas found in the adjacent 
premontane tropical wet forest (Young 1980b) as studied about 25 
km from the Cuesta Angel locality. Young (1975) found only two 
genera, each monospecific, at another montane wet forest locality, 
Bajo La Hondura. There are also greater numbers of genera and 
species found in mid-elevation moist forest (Young 1980a) and 
lowland tropical dry forest (Young 1981a) in Costa Rica. Cicadas 
such as F. sericans and F. mannifera are tentatively interpreted as 
being ecological “leaks” into the forested ravine at Cuesta Angel. 
Given the continuous accessibility to lower elevation wet forest 
habitats moving along the ravine into the lowlands, it is un- 
reasonable to expect some highly mobile insects to colonize at either 
end (Young 1975b). 
Elsewhere in Costa Rica, cicadas have been found to have distinct 
seasonal patterns of adult emergences each year (Young 1972; 
1975a; 1980a, b; 198 la, c) with the recognition of usually three kinds 
of cicadas: dry season, wet season, and transitional forms between 
dry and wet seasons. From the studies of cicadas in premontane 
tropical wet forest in particular (Young 1980b), however, it became 
apparent that brief spells of wetness in a dry period and of dryness 
in the wet season may trigger emergence of wet season and dry 
season species respectively. In the premontane tropical wet forest 
zone of northeastern Costa Rica, typically wet season cicadas such 
as Z. smaragdina Walker will emerge in low numbers during a rainy 
spell of about five days or longer within the dry season (Young 
1980b: pers. obs.). During a dry spell within the long rainy season at 
the same locality, F. sericans, a typical dry season cicada, can also 
be heard and fresh nymphal sLins found (Young 1980b; pers. obs.). 
Such observations indicate that “seasonality” in tropical cicadas is a 
very flexible sort of emergence strategy, perhaps determined by 
critical periods of wetness or dryness, depending upon the species 
and locality. Such an effect may explain the anolamous emergence 
of F. sericans in the wet season at Cuesta Angel. The data from 
Cuesta Angel very tentatively provide additional support for this 
phenomenon, as shown for species such as F. n.sp. The proximal 
cues triggering emergence in tropical cicadas have not been studied 
to my knowledge, although some ideas have been suggested for 
study (Young 1975; 1980a, b; 1981a). What are also needed are 
detailed studies of the effects of small changes in air temperature 
and humidity, and light intensity on the behavior of adult cicadas in 
