1983] 
Henry — Chrysoperla plorahunda 
351 
pooled from all ten individuals, over 95 percent of variance is 
explained by regression line A shown in Figure 3. Even for the worst 
case — terminal volley frequency — nearly two-thirds of raw data var- 
iance is compatible with the calculated linear regression (r- = 0.65). 
And data for individuals are neither more nor less variable, on 
average, than pooled samples: for the five principal call features 
graphed in Figure 3, individual r- values average 0.93, 0.84, 0.59, 
0.79 and 0.76 and never fall below 0.40 for any single insect. Also 
shown in that figure is the close congruence of all individual lines for 
each of the same five call features but particularly for initial volley 
frequency, suggesting that such temperature relationships are con- 
sistent, repeatable, and predictable on an individual basis. 
Results of experiments manipulating abdominal mass in individ- 
ual lacewings are shown in Figure 4 and Table 2. Table 2 presents 
the raw temperature-frequency data taken from four insects, while 
Figure 4 shows how those data relate to the linear regressions gener- 
ated from the terminal volley frequencies of the ten unmodified 
individuals tested earlier. Converting the frequency measurements 
to their equivalent values at 27°C (Table 2) dramatically reveals 
how little those data are affected by mass-loading of the abdomen: 
in none of the four experimental animals was the terminal volley 
frequency altered significantly by the treatment. Weight increments 
(from painting) amounted to 10-27% of total body mass; however, 
abdominal weights were only 2.8 mg for the female and approxi- 
mately 2 mg for the three males, so increments to the mass of the 
vibrating structure itself in each insect actually ranged from 36 to 
50%. 
Discussion 
The results described above amply document the striking similar- 
ity of male and female calls of Chrysoperla plorahunda, consistent 
with the proven importance of such signalling behavior to the 
reproductive isolation of this species from several of its morphologi- 
cally identical siblings in the genus (Henry 1980b, 1983b). Females 
closely resemble males in every detail of volley structure and spac- 
ing, and those few differences that do exist in pooled samples tend 
to break down when the characteristics of individual insects are 
compared (Figs. 3 and 4). Also as predicted, males and females 
