1983] 
Henry — Chrysoperla plorabunda 
353 
change their various call characteristics in precisely parallel ways as 
temperature is altered, so that the sexes’ calls remain indistinguish- 
able over the range of temperatures they would typically encounter. 
The only apparent exception to this conclusion concerns the slightly 
lower vibration frequencies characteristic of the terminal portions of 
the volleys of females at all temperatures (Fig. 2C). Such a differ- 
ence is expected if the terminal volley frequency of a lacewing’s 
abdomen is determined by its inherent capacity to oscillate like a 
weight on a spring, since the demonstrabty heavier abdomen of a 
female would resonate at a lower frequency than that of a male. 
However, artificially mass-loading the abdomens of several males 
and females produced no obvious downward deflections of their 
frequency characteristics, suggesting that neuro-muscular mecha- 
nisms actively “drive” the vibrating system for the entire duration of 
each volley (Table 2) and that resonance effects have relatively little 
influence on resultant frequencies. Also, as mentioned earlier, the 
male-female difference in terminal volley frequencies is considerably 
less impressive when the responses of individual insects are dissected 
from the pooled data (Fig. 4), thus raising the suspicion that it is an 
artifact of some sort. 
Studies of other acoustical insects overwhelmingly support the 
existence of linear functions relating temperature to most song 
parameters that repeat over time, as best exemplified by and 
documented for rates of wing-stroking, chirping, and “rolling” in 
crickets (Alexander 1956, Walker 1962, Dumortier 1963, Prestwich 
and Walker 1981) and a few katydids and homopterans (Dumortier 
1963, Shaw 1968, Whitesell and Walker 1978, Booij 1982). Similarly, 
most of the temperature data reported here for Ch. plorabunda 
conform well to linear statistical models, although they are insufficiently 
detailed to discriminate linear from exponential interpretations. The 
least individual or pooled variance from the calculated regression is 
found for the abdominal vibration frequency of the first eight cycles 
of a volley, suggesting that this feature of the call is particularly 
crucial to unambiguous communication between the sexes; otherwise, 
it seems there would exist no need for such precision. 
In his 1962 paper on cricket song. Walker drew attention to the 
apparent convergence of many of his linear regressions on 4°C; 
that is, it seemed that for many different cricket species the chirp 
