Pesticides cause serious damage to agricultural and natural ecosystems. Knowing pesticides' side effects on non-target beneficial phytoseiids is crucial for integrated mite management (IMM) programs. One solution is to use biological agents and a low concentration of pesticides together. The present study was conducted to evaluate sublethal effects of acaricide Milbemectin (Milbecnock®) at LC₅, LC₁₅ and LC₂₅ levels on development and reproduction parameters of Amblyseius swirskii Athias-Heneroit (Acari: Phytoseiidae) under laboratory conditions [25 ± 1°C, 70 ± 5% RH and 16:8 (L:D) hours]. Our results demonstrated that higher concentrations of Milbemectin (LC₁₅ and LC₂₅) had the most effect on the Longevity and the Total life span of both males and females of a predatory mite. The total life span in females was recorded from 42.67 days (Control) to 23.46 days (LC₂₅ treatment). In an unusual observation, the oviposition period and also the total fecundity of the LC₅ treatment have been 21.42 days and 37.31 offspring per individual, respectively. Which is recorded higher than the control treatment. These parameters were recorded in minimum value on the highest concentration treatment. Contrariwise the intrinsic rate of increase (r) and the finite rate of increase (λ) are not affected by sublethal concentrations of Milbemectin. The recommended dose of milbemectin based on the active ingredient is 10 ppm and the concentration obtained for LC₅ is 27.92 ppm, which had a positive effect on fecundity and a slight imperceptible effect on the total life span reducing of the predatory mite. Sublethal effects of milbemectin and its impact on A. swirskii are discussed.