Aspects in the ecology of Maltese odonata

Abstract

The present work reports on three investigations concerning the Odonata of the Maltese Islands. The distribution of dragonflies and damselflies in the Maltese Islands was studied, by observing different localities and listing down the species found during each season. The development of a dragonfly larval assemblage in one locality was studied, by taking periodic samples of the population and measuring larval head width and body length. The growth rate of larvae of different species was monitored in the laboratory, by again measuring body length and head width. Five species of Odonata; A.imperator, C.erythraea, S.fonscolombii, O.cancellatum and Igenei are widespread throughout the Island, while the rest are restricted to a few localities, especially members of the genus Orthetrum which are restricted to areas with freshwater courses. Larvae of Igenei, S.fonscolombii, and C.erythraea were found living in brackish water at il-Magħluq (M'Xlokk) and il-Magħluq (M'Scala). The larval phase of these is less than one year, therefore the larvae would not die off in summer when the water pools dry up. Freshwater reservoirs are also used as sites for breedng by dragonflies. In fact larvae were found to live here even in summer. During the mating phase, males were more abundant than females. Thus there is competition for females. Males of most species are territorial, and territory holding, males chase away males of the same species from their territory, but were not usually aggressive towards other species.