Abstract: An extended laboratory bioassay was conducted to evaluate the toxicity and theduration of the harmful activity of some modern insecticides and the standard deltamethrin to thebraconids Aphidius ervi Haliday (aphid parasitoid) and Chelonus inanitus L. (Spodoptera eggsparasitoid). Adults were initially exposed to fresh residues on tomato leaves for three days, andlater on, to aged residues in greenhouse. Fresh residues of flonicamid, flubendiamide andspirotetramat were harmless to both parasitoids. Metaflumizone, however, was classified asmoderately persistent for C. inanitus (IOBC C) and persistent for A. ervi (IOBC D), due to thereduction on the life span. Deltamethrin was slightly persistent (IOBC, B) and persistent, (IOBC,D) respectively, for the two natural enemies.