1968] 
Robinson — Behavior of Pterinoxylus 
199 
Figure 2. A. Display of male P. spinulosus showing vertical wing erec- 
tion and commencement of body flexure. 
B. Bizarre attitude assumed after display by male P. spinulosus , 
(Based on photographs by N. D. E. Smythe). 
expanded the wings are moved against the tegmina. as shown in 
Figure 3. This movement enhances the conspicuousness of the dis- 
play and adds the acoustic component. Wood-Mason (1877) de- 
scribed stridulation in a species of Pterinoxylus (possibly P. spinu- 
losus , see Rehn 1957) as occurring when the rasps on the superior 
surface of the costal area of the wings “are scraped by the sharp 
and hard front edge of the tegmina”. This statement implies, per- 
haps unintentionally, that the tegmina are the active members. In 
fact, analysis of movie film of the wing movements suggests strongly 
