1983] 
Henry — Chrysoperla plorabunda 
347 
Discussion sections to “significant differences” indicates that the 
means of two normally distributed samples were demonstrated to 
differ from one another by a 2-tailed t-test using confidence limits of 
95% or better. Values following a +/- sign are one standard 
deviation of the mean. 
Results 
I measured five different characteristics of the calls of Chryso- 
perla plorabunda males and females. These are listed and defined 
below and illustrated in Fig. 1 
A. Initial volley frequency: The cycling rate per second of the 
first eight strokes of the abdomen, at the start of a volley of 
abdominal vibration. 
B. Median volley frequency: The cycling rate per second of the 
eight abdominal strokes following the initial period defined 
above. 
C. Terminal volley frequency: The cycling rate per second of 
the abdominal strokes that remain in a volley after A and B 
have been deleted. 
D. Volley repetition rate: The rate per minute at which a calling 
lacewing produces volleys of abdominal vibration. 
E. Volley duration: The length of time in seconds required for 
completion of a volley of abdominal vibration. 
Frequency of abdominal vibration versus temperature is tabu- 
lated for all males and females in Table 1 and expressed as linear 
regressions for each sex in Figure 2. Since vibration frequency 
decreases during the course of a plorabunda volley, it is necessary to 
subdivide each volley into the three portions A, B, and C, defined 
above; frequencies measured for those portions are plotted sepa- 
rately on the graph. Other call parameters like volley repetition rate 
and volley duration are similarly plotted separately for each sex on 
the same figure, using different units on the y-axis. All data are 
combined for both sexes in Figure 3, which also displays the range 
of variation in the calculated regression lines for all 10 individuals. 
Several obvious features emerge from these tables and plots. First 
of all, it appears (Table 1) that males and females differ from each 
