Entomological biodiversity plays a crucial role in maintaining the ecological balance of agroecosystems by providing essential ecosystem services such as pollination, pest regulation, and the decomposition of organic matter. In this context, the present study assessed the diversity and structure of entomofauna in agroecosystems under semi-arid climatic conditions. The study was conducted from February to May 2025 in apple (Malus domestica) and peach (Prunus persica) orchards located in Aïn Oussara (Djelfa, Algeria). Insect sampling was carried out using yellow sticky traps (20 × 25 cm), with one trap installed per hectare in the canopy of randomly selected trees. A total of 4,614 individuals were collected, belonging to 7 orders, 51 families, and 95 species. In terms of abundance, the order Thysanoptera was the most represented in both orchards. Within this order, the predatory species Aeolothrips fasciatus was dominant, accounting for 19.70% and 21.44% of the total captures in the apple and peach orchards, respectively, and exhibiting a constancy of 100% in both orchards. Regarding species richness, the order Hymenoptera was the most diverse. Ecological index analyses revealed high species richness, a relatively even distribution of individuals, and a well-structured entomological community in both orchards. The analysis of functional guilds showed that phytophagous insects were the most abundant and species-rich group, followed by predators in terms of abundance and parasitoids in terms of species diversity. These findings provide valuable insights into entomological biodiversity and trophic guild composition, both of which are essential for maintaining ecological balance and promoting natural pest regulation. Moreover, the identification of 25 parasitoid species and 9 predatory species highlights their potential use in biological control programs.