376 
Psyche 
[Vol. 88 
soperla rufilabris (Burmeister), C. downesi (Banks) and C. carnea 
suggest that “acoustical” communication may help to reproduc- 
tively isolate sympatric lacewing species. 
Since the vibration produced by abdominal jerking in lacewings 
seems to be propagated in a transverse wave (perpendicular to the 
plane of the substrate) we prefer to call this type of communication 
“tremulation”, following Busnel et al. (1956), Henry (1980c) and 
Morris (1980). On the other hand, sound in the form of longitudinal 
waves, is produced by stridulation and percussion. Possible stridula- 
tory structures in lacewings were first described for the chrysopid 
Meleoma schwarzi (Banks) by Adams (1962) and later for other 
Neuroptera (Riek 1967). However, to date, there is no reported 
record of any sound produced by these organs (Henry 1980c). In M. 
schwarzi, sound may be produced when the second abdominal 
sternite, with its regular striae of microtrichia, is rubbed against the 
femora by abdominal vibration (Adams 1962). C. carnea and some 
other species of Chrysopidae may stridulate using microtrichia on 
the venter of the anal lobe of the forewings and dorsolaterad on the 
metanotum (Riek 1967; Henry 1979). Alternatively, these paired 
areas of microtrichia may function to hold the wings in place when 
at rest (Henry 1980c). Thus, tremulation and possible stridulation 
are both produced by vibrating the wings and abdomen. 
Methods and Materials 
Observations of free flight and mating behavior were made on the 
following species: C. carnea, Eremochrysa punctinervis McLachlan, 
E. tibialis Banks, Mallada basalis (Walker), Meleoma hageni Banks 
and Nodita n. sp. The only specialized technique required for this 
study was the use of a strobe light to illuminate lacewings on a flight 
mill (Duelli 1980). By varying the frequency of the strobe flashes, it 
was possible to determine the rate of the wing beats and other body 
movements, as the highest flash frequency at which the motion 
appeared to be “frozen” and each structure was seen in only one 
position. A multiple of this frequency again produces a frozen 
image, but the body is seen in multiple positions. C. carnea and M. 
basalis were examined in this manner. 
Results 
Among the species observed, there appeared to be great variation 
in the patterns and intensities of vibration of the wings and 
abdomen during courtship, but this was not quantified. The beha- 
