1979] 
Henry — Chrysopa downesi 
295 
Figure 1. Oscillographs of abdominal vibration patterns produced by courting 
individuals of Chrysopa cornea (A, B) and C. downesi (C, D). Duets between a 
sexually receptive male and female are recorded in (A) and (C) at an oscilloscope 
writing speed of 2 seconds/major division; in C. carnea, each insect exchanges single 
volleys of abdominal jerking with its partner, while in C. downesi, whole sequences of 
volleys are exchanged. Individual volleys for each species are shown in B (C. carnea, 
male) and D (C. downesi, male), recorded at a writing speed of 0.10 second/major 
division. For C. downesi, volleys typical of part 1 and part 2 of the sequence are 
indicated. 
