Studies on the roosting behaviour of Palpopleura lucia lucia (Drury) and Acisoma panorpoides inflatum Selys (Anisoptera: Libellulidae)

Roosting behaviour was studied in P. l. lucia and A. panorpoides inflatum between October, 1972 and March, 1974. The roosting postures of the two species were described and compared with their normal perching postures at water. Measurements of the bearings of the insects during roosting indicated that there were no orientational preferences. The dragonflies roosted within the same locality but were not restricted to definite plants. The duration of roosting was slightly longer than the night hours at Ibadan, Nigeria, for all months of the year. It was concluded that light intensity was the overriding factor initiating roosting and the first flight of the day.