Despite their abundance and worldwide distribution, Opiliones are still a very poorly known order, and their trophic relationships are under-researched as well. They are primarily predators of smaller invertebrates, but also opportunistically feed on carrion and plant matter, which is why they affect the ecosystems they are a part of in multiple ways. This work aimed to determine the fauna and ecological characteristics of Opiliones in Mediterranean agricultural ecosystems. Morphological determination of the individuals sampled in the vineyards and olive groves of Zadar County was carried out, as well as analysis of the composition and abundance of species and DNA metabarcoding of gut contents of selected individuals. The obtained data was compared with data on the diversity of other groups of invertebrates collected during field research as part of the same project. Four species of harvestmen were morphologically identified. The most numerous was Phalangium opilio Linnaeus, 1758, and there was one endemic species of the Western Southeast Europe, Astrobunus dinaricus Roewer, 1915. DNA metabarcoding revealed ten species and two families of invertebrates, of which three species were potential agricultural pests. This research gives an insight into a small but promising part of the diversity and role of harvestmen in vineyards and olive groves, and further research is needed to clarify their significance in these ecosystems.