[Vol. 91 
148 Psyche 
1 . 
20 30 40 50 60 
Copulation duration (sec) 
Figure 3. The relationship between the mass of material passed by a male at 
copulation and the duration of copulation. 
The quantity of material passed by a male was not related to his 
size, contrary to observations made by Boggs (1981) on a heliconiine 
butterfly, Greenfield (1982) on a pyralid moth, and Gwynne (1982) 
on a katydid. However, males, independent of size, produce a 
typical quantity of material during a copulation and the proportion 
of a male’s body mass passed varies inversely with male size. 
Because of the critical role inflation of the bursa copulatrix plays in 
