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although the best there are at this time. With the exception of C. 
postica, there appears to be a trend for most species to emerge 
during both wet and dry seasons, when considering both the 
nymphal skin and call records together. Thus although F. sericans is 
heard in abundance during the short dry season, there is some 
evidence of emergence well into the wet season (Fig. 6). But 
examining the 1973 rainfall data shows a marked dip in rainfall 
during July (Fig. 2), giving a brief dry spell that month. If it is 
assumed that the data are actually representative of emergence 
patterns of cicadas at Cuesta Angel, it then appears that another dry 
season species, C. postica, did not respond to the July 1973 dry spell 
as there was no emergence (Fig. 6). At the same time, the dry spell 
was apparently insufficient in intensity to block the emergence of 
wet season species such as Z. tympanum. Perhaps even more 
interesting is the wet season emergence of another supposedly dry 
season species, F. n.sp. (Fig. 6). Adults of such species were not 
heard at these times although my sample sizes are very small. 
Different patterns of emergence may be associated with different 
years in whch monthly rainfall regimes are very different. For 
example, during 7-9 May 1975, there was an abundance of F. n.sp 
calling in the ravine as was the case for 4-7 July 1973. Both of these 
months, in different years, were drier than in other years, and the 
rainfall data for 1972 and 1973 clearly show the year-to-year 
variation in monthly rainfall patterns at this locality (Fig. 2). 
Furthermore, when F. n.sp. emerged during the wet season, calling 
was restricted to the dry periods of the day. All of the cicadas 
studied exhibit bursts of calling near dusk (see also Young 1981b). 
The distribution of nymphal skins for each species studied by 
marked trees is given in Table 1. Even though approximately 70 
species of canopy-size trees were included along the initial transects 
to determine the locations of cicada emergence patches in the 
ravine, patches were found to be confined to the species of 
Leguminosae listed in Table 1. Note that the estimation of relative 
abundance of adults among the species discussed above is confirmed 
here in terms of nymphal skins: by far the most abundant species is 
F. sericans, whose nymphal skins comprised almost 64% of the total 
241 skins collected in the 1973 survey of tree plots alone (Table 1). 
F.n.sp., Z. tympanum, and Carineta sp. are about evenly distributed 
in terms of abundance of nymphal skins in the tree plots. As in 
previous studies of cicadas in Costa Rica, sex ratios are close to 
