At the "Alexandru Ciubotaru" National Botanical Garden (Institute), during the growing seasons of 2021 and 2022, surveys were carried out to record the useful and pathogenic entomofauna of the species Onobrychis arenaria (Kit.) DC, known as a high-potential melliferous and fodder plant. The entomological monitoring was carried out during the period April-June, which coincides with the budding-flowering stage of the plants. A wide range of insect species was detected, with an essential impact on the pollination process of the sainfoin flowers, during this period. The systematic classification of insects was performed and their trophic specialization was determined. There were insects that, in the trophic chain, are found in the category of phytophagous species, which feed on nectar, pollen and other plant liquids, as well as zoophagous species. Overall, 12 species were identified, being classified into 4 orders (Homoptera, Hymenoptera, Coleoptera, Hemiptera), 8 families (Aphididae, Apidae, Formicidae, Cantharidae, Coccinellidae, Pentatomidae, Pyrrhocoridae, Cerambycidae) and 10 genera (Aphis, Apis, Agapanthia, Bombus, Formica, Lasius, Cantharis, Coccinella, Dolycoris, Pyrrhocoris). Analyzing taxonomically the insect populations, it was found that the maximum share belongs to insect species of the order Hymenoptera (50% of the diversity of insect species), insects of major importance for the plant world, honeybees and pollinators – Apis mellifera L., Bombus terrestris L., B. lapidarius L., B. hortorum L.