1979] 
North & Shaw — Pterophvlla camellifolia 
365 
This study is a detailed analysis of the geographic distribution of P. 
camellifolia in Iowa and a more extensive characterization of popula¬ 
tion differences based upon both behavioral (parameters of male 
calling sounds) and morphological characters. 
Methods 
We determinted the distribution of P. camellifolia in Iowa during 
the summers of 1975-1978. Colonies (disjunct groups of katydids) 
were located by driving at reduced speeds along rivers and stopping at 
approximately 1/2 km intervals to listen for the loud choruses of 
calling sounds. Forest preserves and state and county parks were also 
surveyed throughout the state. 
Surveys in 1975 and 1976 indicated that northwestern and north 
central Iowa, areas with relatively little forested lands, were void of P. 
camellifolia. These surveys, as well as records of previous investiga¬ 
tors (Froeschner 1954, Shaw and Carlson 1969), suggested that an 
extensive survey of gallery forests along certain rivers, e.g., Cedar, 
Des Moines, Iowa, Racoon, Skunk, in central, southern, and eastern 
Iowa would be most productive. During the surveys, exact locations 
of katydid colonies were recorded on county maps. Other data taken 
included: 1) written records of chirp pulse numbers from 10 to 20 
katydids per colony, 2) tape recordings of calling sounds for 5 to 10 
katydids per colony, and 3) collection of specimens whenever 
possible. 
P. camellifolia is a large, flightless, green katydid that resides near 
the tops of tall trees in oak-hickory forests. Males stridulate only at 
night and in Iowa this takes place from the last of July until the first or 
second frost in October. Thus, it was necessary to locate the calling 
male in a tree, climb the tree, spot the katydid with a light, and 
capture it by hand. 
Calling sounds were recorded on a Nagra III tape recorder. An 
American electrodynamic microphone (Model D33) mounted in a 38 
cm aluminum parabolic reflector allowed recordings of individual 
katydids. Ambient temperature was taken at the site of each tape 
recording. 
Pulse rate was determined from audiospectrograms made with a 
sonagraph (Kay Vibralyzer). Pulse intervals and lengths were deter¬ 
mined to the nearest 0.01 second. 
