While the value of linear farm habitats for the protection and enhancement of farmland biodiversity in general is known, less is understood about their contribution to Diptera, especially those with different ecological requirements. In this study, we examined the impact of a range of linear farm habitats in agricultural grassland on Syrphidae and Sciomyzidae (Diptera) both of which provide important ecosystem services. Species richness and abundance for each family were measured across five different linear habitat types (dense and open hedgerows with/without adjacent watercourses and watercourses only). While dense hedgerows with adjacent watercourses showed the greatest numbers of Syrphidae species and individuals, open hedgerows with adjacent watercourses had significantly more Sciomyzidae species and individuals than dense hedgerows without watercourses or open hedgerows only. Syrphidae species richness was significantly correlated with the flowering plant species richness of linear habitats, while Sciomyzidae species richness was correlated with a habitat quality score for grasslands adjacent to the linear habitats. Overall, Syrphidae and Sciomyzidae species richness and community composition are shown to reflect a farming intensity gradient with significantly greater species richness for both families on extensive farms. Our results suggest that different dipteran taxa which utilise linear habitats may have different requirements. This has implications for future agri‐environmental schemes in the context of how we assess the conservation value of linear habitats on farmlands.

The intensification of farming practices, along with the loss and fragmentation of semi‐natural habitats within agricultural areas, has contributed significantly to insect decline worldwide including flower‐visiting aculeate Hymenoptera. In this study aculeate Hymenoptera were collected using bi‐directional Malaise traps placed along farmland linear habitats across a range of farming intensities. The aim was to further our understanding of the value of farmland linear habitats to this insect group and in particular the Vespinae, an understudied subfamily. Overall, significantly greater aculeate Hymenoptera species richness was found on extensive than on intermediate and intensive farms. Significantly more species and specimens were collected on the side of the traps adjacent to the linear habitats compared to the side which opened onto the fields. Aculeate Hymenoptera species richness was also significantly greater in dense hedgerows than in open hedgerows. Furthermore, two out of six Vespinae species, Vespula rufa and Vespula vulgaris, had significantly more individuals on extensive than intensive farms. This study highlights that low‐intensity farming practices and farmland linear habitats, especially dense hedgerows, may enhance aculeate Hymenoptera occurrence in agricultural areas. It also demonstrates that Malaise traps set up along linear habitats across a range of farming intensities can make a significant contribution to knowledge regarding the biodiversity value of such areas. Given that selected Vespinae species follow similar trends to aculeate Hymenoptera, the possibility of using them as simple biodiversity indicators is worthy of further exploration.

Marsh flies are a diverse family that provide valuable ecosystem services, including the biological control of mollusks that are agricultural pests and vectors of animal and human parasitic diseases. In addition, some species may serve as important ecological bioindicators. Despite the extensive research on this family, most have centered on larval diet and behavior, as this is the life stage primarily used for biological control; virtually nothing is known about the natural dietary components of adult marsh flies. Our study aimed to close this knowledge gap by examining the dietary range and preference of adult marsh fly species. Individual flies were provided with five food choices in cafeteria-style food choice trials, consisting of crushed snail, freshly killed slug, glucose solution, honey-yeast mixture (the standard laboratory rearing diet), or water. Sciomyzidae at family level displayed significant differences in food selection (P = 0.0212), with carbohydrates (honey-yeast and glucose solution) significantly preferred over protein options (mollusk tissue) or the water control (P < 0.001). This suggests that marsh flies may naturally maintain a carbohydrate-rich diet. Because many plants typical at field sites produce little or no nectar, a second experiment aimed to determine the source of these carbohydrates in nature. When presented with honeydew harvested from aphids (Hemiptera: Auchenorrhycha), Tetanocera elata Fabricius (Diptera: Sciomyzidae) individuals were observed to feed on dry honeydew and honeydew solution significantly more frequently than the water control (P < 0.001 and P = 0.01969, respectively), suggesting that honeydew may play an important role in adult marsh fly diet.