The present study aimed to throw light on certain biological aspects of the predatory mite Agislemus exsen‘us Gonz. when fed on eggs, immatures and pesticide-treated nymphs of Tefranychus urticae Koch. Results indicated that, duration of immature stages of A. exsertus were insignificantly influenced by the stage of the introduced prey. The female and male life cycle durated an average of 10.89 and 10.48 days when fed on eggs of T. urticae, while the parallel values were 11.15 and 10.76 days when fed on immatures of the same prey. Female lived longer than male. Longevity of female and male were shorter on immature stages than on eggs of the prey. Feeding on T. urticae eggs resulted greater number of eggs (62.57 eggs) than fed on immature stages (57.22 eggs). Life span for the predator female and male lasted 29.48 and 27.31 days, respectively when mites fed on immatures of T. urticae. This periods were extended to 32.26 and 28.31 days for female and male respectively when reared on eggs of T. urticae. Food consumption of A. exsen‘us female and male stages was significantly affected by the stage of the prey. Means of total and daily devoured prey individuals were obviously increased with successive developmental stages. Female consumed greater number of eggs or immature stages of the prey than male. Longevity, fecundity and food consumption of A. exsertus female were significantly diminished when fed on nymphs of T. urticae treated with certain pesticide. Vertimec was the most deleterious one followed by Challenger and Ortus. while M-pede was the least one in this respect. Generally. conjoint usage of the tested pesticides and A. exsen‘us in IPM may require'applying chemicals and biocontrol agent in sequence separated by time intervals that would be sufficient to minimize toxicity effects on the predator.