1980] 
Young — Ecology of Cicadas 
177 
As shown by 1972 and 1973 rainfall data, the region is very wet 
and with a short and erratic dry season during January and 
February (Fig. 2). For either collections of nymphal skins or 
determination of species active by calling songs or collection of 
specimens, the locality was visited the following dates: 27-30 June 
1972, 14 August 1972, 15-17 February 1973, 20-24 March 1973, 
18-20 April 1973 (beginning of nymphal skin regular censuses), 
22-25 May 1973, 6 10 June 1973, 4-7 July 1973, 7-9 May 1975, 3 
April 1976, 1 and 5 November 1980. Dates of visit included both wet 
and dry periods for this region. During the April 1976 visit. Dr. 
Thomas E. Moore recorded calling songs of the species active at 
that time. 
The 1973 visits were concerned primarily with attempting to 
census the nymphal skins of various species active at different times 
of the year while other dates were devoted to listening and collecting 
adult specimens. The nymphal skins of recently emerged cicadas are 
relatively easy to distinguish from those of a previous years’ 
emergence owing to discoloration and disintegration of some parts 
(Young 1980a) and therefore provide an accurate record of a recent 
or current emergence within the year. The locations of nymphal 
skins in the habitat also provide information on the possible feeding 
associations of the nymphs in the ground and other aspects of 
microhabitat. I censused nymphal skins, with the assistance of at 
least one, and usually two, trained student assistants by marking off 
rectangular or square plots (usually 5X5 meters) immediately be 
neath a tree or other spot where at least one nymphal skin was 
found. Initially we crawled through the forest along transects to 
determine where nymphal skins were found and then marked off the 
trees and places having them. The transect approach was used in the 
survey of the very rocky terrain comprising the river-edge forest on 
relatively flat ground, but working on the steep slopes entailed spot- 
checking various places owing to the difficulty of the terrain and 
often very misty conditions. Thus the nymphal skin census program 
involved repeated censuses at twelve marked canopy-size trees on 
the slopes, and four large river-edge plots of forest, each plot 
containing many trees. The four river-edge plots, each one widely 
separated from the other by at least 100 meters of forest, ranged in 
size from 462m 2 to 300m 2 , the differences being due to rivulet 
channels and other interruptions in the forest. With the exceptions 
of marked trees 2, 6, and 7 (each of which was a plot of about 90m 2 ), 
