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[Vol. 88 
unity. Taking the most abundant species, F. sericans, there is 
considerable range in numbers of skins found in the different tree 
plots, although close to 40% of all skins of this species were found 
beneath one individual of Pithecollobium latifolium (Table 1). Yet a 
second individual of this tree species yielded only four skins of 
cicadas overall and none of F. sericans. Such data, although limited, 
indicate the considerable variation encountered over different 
patches of the same resource for a cicada species in tropical forests. 
Two different individuals of Inga and one P. latifolium together 
account for almost 65% of all skins found. That such data may be 
underestimates of true values, even for an abundant species such as 
F. sericans, is suggested by the results of the estimate of rate of 
disintegration of nymphal skins: at the end of a five-week period, 
between 50% (level ground) and 80% (slope) of the F. sericans 
nymphal skins studied had disappeared. These samples are pitifully 
small, but it is the best we have at this time. The intervals between 
censuses in my study are of this magnitude and greater, thereby 
indicating the likelihood that some skins were missed owing to their 
rapid disintegration under very wet conditions. The examination of 
nymphal skin distributions by tree plots and river-edge plots 
separately provides further confirmation of the data shown in Table 
1 (Table 2). Although high percentages, if not all, of plots are 
occupied by skins of Z. tympanum, the emergence is one of very low 
density since only a small number of skins occur in the plots studied 
(Table 2). The tree plots, although only representing an area of 
about 6.5% of the combined area of tree plots and river-edge plots, 
account for almost 80% of all skins recovered (Table 2). The larger 
river-edge plots include a wide variety of tree species whereas the 
tree plots each include one individual of a leguminous tree species 
and understory plants. Most striking is the relatively high density of 
the nymphal skins of F. sericans in the tree plots, almost 0.4 
skins/ m 2 (Table 2). Yet the same cicada, in a much larger and 
representative tract of forest, representing an area about five times 
that of the tree plots, has the very low density of about 0.010 
skins/ m 2 (Table 2). Other patterns of nymphal skin density between 
tree plots and river-edge plots are self-evident and support the 
pattern discussed for F. sericans (Table 2). From such results, one 
can readily appreciate the distortion of density estimates when 
different size patches of the environment, with different biological 
attributes, are combined to give a summary figure (Table 2). And 
