Initial preference of oviposition sites: discrimination between living and dead plant material in Sympecma fusca and Coenagrion caerulescens (Odonata: Lestidae, Coenagrionidae)

Abstract

Sympecma fusca and Coenagrion caerulescens mainly deposit their eggs into floating dead parts of emergent plants. In their initial choice of oviposition site (selection of landing site) S. fusca does not distinguish between fresh and dead plant material, whereas C. caerulescens significantly prefers dead material. In S. fusca, the missing discrimination of the plant condition in the choice of the landing site is explained by its oviposition period in the beginning of the vegetation period when the green plant material is rare. C. caerulescens reproduces in summer and finds dead and living plants side by side. I suggest that in the latter species an early recognition of dead material is advantageous because of the reduction of the expense in searching.