Aphids (family Aphididae) are a major problem in agricultural production because they are prone to insecticide resistance development. Therefore, the use of biological protection measures is highly recommended. The parasitic wasp Aphidius colemani Viereck (Hymenoptera: Braconidae) has been successfully used in the biological control of many economically important aphids, especially the cotton aphid (Aphis gossypii Glover) and the green peach aphid (Myzus persicae Sulzer). This study aimed to determine the residual activity and persistence of a novel insecticide (A19526X) on adult Aphidius colemani parasitic wasps. The study was performed by foliar treatment of pepper plants in six variants, each in four replicates: a new tested insecticide (A19562X) in three doses, two systemic insecticides (spirotetramat and imidacloprid) and control. The treated plants were placed individually in cages. Adult Aphidius colemani individuals were released into cages 24 hours and seven days after insecticide application. The mortality was read 48 hours after the wasps were released. Imidacloprid, as a standard systemic, proved to be most effective on the parasitic wasp and persisted for nine days after treatment. Spirotetramat had a negligible effect and proved safe for this wasp. The investigated insecticide A19526X showed poor residual activity on the A. colemani. It was poorly persistent on the eighth day after treatment, and on the ninth day it had an efficacy of 23.5%. Given the results, the insecticide A19526X can be considered safe for natural enemies in the control of aphids, since it does not significantly affect the parasitic wasp mortality. Further studies of persistence duration, as well as effects on other developmental stages of the wasp, are certainly recommended for a better conclusion on the safety of the investigated insecticide for natural enemies.