The reproductive behaviour in relation to structural habitat resources was studied at mountain bogs of the Central Alps (Tyrol, Austria). The 3 â searched for mates at small clearings in coniferous forests where numerous scattered oviposition sites were hidden in dense vegetation, using 3 tactics: (1) they scanned the oviposition sites by slow flights at low height over large vegetated areas (scan flight), (2) they patrolled restricted areas with frequent hover stops while chasing any intruder (patrol flight), (3) they dived repeatedly into gaps of emergent vegetation, searching for 9 9 close to the water (dive flights). 62% of the 9 9 remained undiscovered by 63, 11% fled successfully and 27% accepted copulation (n = 139). The copulation was always initiated in the air or on the ground when both partners plunged into the vegetation following a clash. Immediately after the take off — and possibly after intramale sperm translocation — the tandem assumed the wheel position. The pairs often circled over the clearings for several minutes and perched on sunlit branches of spruce or pine trees, 0.8-12 m above ground (mean 2.75 m, n = 20). During copulation that lasted 31-150 min (mean 85 min, n = 14) rhythmic pumping movements of the 3 basal abdominal segments with frequencies from 0,14 to 0.36 Hz were observed. Copulation terminated by disengagement of the genitalia, then the partners separated immediately or after a short tandem flight. Oviposition never followed directly upon copulation and always occurred unguarded. The oviposition sites were selected carefully at shallow puddles among emergent vegetation. Eggs were laid by touching soaked moss or turf mud with the tip of the abdomen during rhythmic dipping flight movements with mean frequency of 0.61 Hz. One oviposition bout lasted 1-3 min and featured an egg flow of 1.7-4.5 eggs per s. Ovipositing females were sometimes successfully attacked by frogs (Rana temporaria), and males were occasionally found in orb-webs of spiders (Araneus sp.); however, predation risk was low at rendez-vous sites. Sperm competition is discussed with respect to behaviour during copulation and to the morphology of 3 and 9 genitalia.