The behaviour of adults closely before and during rainfall at Shillong, India, is brought for the first time on record for an euphaeid dragonfly. The behaviour and wing posture during the rain are in agreement with the observations on European Galopterygidae. The wing posture during cloudy weather, however, is different from that in Calopteryx. An annotated review is given of the literature on the euphaeid behaviour, and it is stressed that, contrary to B. indica (Sel.), B. hyalina is an essentially arboreal species.