Boyeria cretensis belongs to the most threatened European dragonfly species. It is restricted to some isolated permanent streams on the island of Crete. The streams have a pronounced gallery vegetation and are situated in a narrow belt of altitude between 50 and 400 m. We understand very little about the biology of this species so…
The large Neotropical zygopterans Megaloprepus caerulatus, Mecistogaster linearis and M. ornata (Pesudostigmatidae) were surveyed during five years, and striking differences in their reproduction patterns were shown: (1) At two study sites in seasonal, tropical semi-dry forests in Pacific Costa Rica, adult M. ornata could be observed throughout the year, occasionally during the dry season up…
In a recent paper D.R. Paulson (2004; IJO 7: 505-515) presented five hypotheses concerning the way wings are held in the Zygoptera during perching. A critical examination suggests that most of them have substantial flaws that prevent their testing. Based on Bechly’s phylogeny (1998;
Zygoptera show two perching modes, one with wings closed and one with wings open. These perching modes are distributed unequally through the suborder; most Zygoptera perch with closed wings, but species in 43 genera of eight families at least occasionally – in most cases usually – perch with open wings. Alternative hypotheses to explain this…
The article considers the phenomenon of ballistic defaecation by odonate larvae, exhibited by certain Anisoptera but not by any Zygoptera, and explores two possibilities: (1) that ballistic defaecation in Anisoptera may correlate with increased foraging success (the ‘Wudkevich Hypothesis’) by distancing the prey’s alarm pheromone, persisting in the pellet after defaecation, from the larva’s ambush…
The effect of copulation and presence of predators on territorial behaviour of male Calopteryx haemorrhoidalis (in southern France) and of male C. splendens splendens (in northern Germany) was studied in nature. A male obtaining a copulation early in the day often secured more copulations later that day than did males not obtaining an early copulation….
Final-instar exuviae left at the emergence site by Odonata can provide information of high quality for measuring sex ratio, especially of Anisoptera. Criteria are listed according to which counts of such exuviae are acceptable for this purpose. Records of sex ratio of Odonata, published and unpublished, are critically reviewed, and 194 that meet the listed…