P. quinta is a tropical sp. with 2 3 morphs: the black-winged (BW) 3 and the hyaline-winged (HW) 3; here their sexual behaviour is described. In general, 6 3 seem to spend relatively little time in flying activities. This may be explained either by the inability to recognise conspecifics and, hence, engage in social interactions, or by the reduced energetic reserves that prevent them from engaging in expensive activities. BW <J 3 were more aggressive and site-faithful than HW <J 6 . BW defended spaces containing debris (plant and wood) against conspecifics while HW did not. BW-BW, BW-HW and HW-HW aggressive encounters were common. Despite their non-aggressive nature toward BW <J <J, HW 3 3 behaved aggressively when faced by HW 3 3. The distance flown by each morph from 3 grasping of the ? until she started oviposition was measured: HW flew longer distances than BW. These differences between 3 morphs are compared to those found in Mnais p. pruinosa, another 3 dimorphic zygopteran. Similar to what happens in that sp., both tactics in P. quinta are possibly maintained due to the similar reproductive and energetic costs accrued by and benefits paid to each morph.