The reproductive behaviour of the damselfly Sclerocypha bisignata (Chlorocyphidae) was studied in various fast flowing streams in mountainous regions of Central Sulawesi. Using high speed cinematography males were shown to exhibit protracted threatening flights with a stationary display of the fore wings. In steady threatening flight the abdomen was held horizontally and the stroking of the hind wings paused briefly and regularly every 2–5 wing beats. These flights were interrupted periodically by short bursts of increased intensity were males arched their abdomens upwards and the hind wing beat was continuous. This flight style differs in several respects from any chlorocyphid species yet studied. During courtship the males presented all three pairs of legs; as courtship intensified they briefly raised their abdomen and presented stationary fore wings. Oviposition took place with the female completely submerged. Unlike most Chlorocyphidae, oviposition sites and male display sites were well separated and ovipositing females were unguarded.