Aphidivorous hoverflies (Diptera: Syrphidae) at field boundaries and woodland edges in an agricultural landscape

The aim of this study was to assess the occurrence and structure of the populations and communities of hoverflies (Diptera: Syrphidae) in particular types of midfield thickets (field boundaries and forest islands) characteristic of the lower Vistula valley. The investigation was carried out in 1998-2001. The midfield thickets were situated in an agricultural area. Syrphids were caught in yellow Moericke traps and with an entomological net. In the agricultural landscape the forest islands were visited by the highest percentage of aphidophagous syrphid species. Such midfield thickets (margins of forest islands) - habitats with a stable and diverse vegetation - can provide an attractive food resource for syrphids. Moreover, they offer hoverflies favourable conditions for shelter and, probably, development. Such habitats are thus key aspects of comprehensive crop protection.