Adult behaviour of Xanthocnemis zealandica McLachlan and Austrolestes colensonis White at selected South Island (N. Zealand) habitats (Zygoptera: Coenagrionidae, Lestidae)

Aspects of adult behaviour of the endemic New Zealand Zygoptera Xanthocnemis zealandica McLachlan and Austrolestes colensonis White are examined. Both species commonly occur together around their aquatic breeding sites, and have similar long flight periods lasting from spring to autumn. No adults of either species were found to be active at air temperatures below 14°C, and they became most active at the highest temperatures and in sunny areas. There was a distinct difference in oviposition sites of the two species. X. zealandica oviposited in aquatic and semi-aquatic plants at and just below water level, depositing one egg at a time; A. colensonis laid eggs in groups inside the stems of plants in or near water, about one metre above it. Mature males patrolled these oviposition areas; X. zealandica males tended to form swarming groups when populations became dense. However, A. colensonis males never swarmed; they probably regulated their numbers by territorial behaviour.