<p>Rising ambient temperatures driven by global warming are subjecting insect populations to thermal conditions exceeding their historical environmental ranges. Understanding how temperature alters key life-history traits is essential for optimizing integrated pest management strategies, particularly for invasive species. This study investigated the effects of short-term thermal stress (31 °C for the parental generation, with offspring returned to 26℃) on life history traits and insecticide sensitivity in the codling moth <i>Cydia pomonella</i> (L.), a major agricultural invasive pest. Results demonstrated that elevated temperature significantly shortened larval developmental duration and reduced pupal weight and overall fitness, with these phenotypic effects persisting across generations. Additionally, increased temperature attenuated the sensitivity of <i>C. pomonella</i> to <i>lambda</i>-cyhalothrin, especially in parental generation. In contrast, reproductive output and sensitivity to chlorantraniliprole remained largely unaffected by thermal elevation. Activities of detoxification enzymes including cytochrome P450 monooxygenases (P450s), carboxylesterases (CarEs), and the antioxidant enzyme catalase (CAT), were significantly upregulated at elevated temperatures, with transgenerational inheritance observed in progeny, potentially contributing to the observed decrease in insecticide sensitivity. These findings advance our understanding of the transgenerational physiological and biochemical adaptions of <i>C. pomonella</i> to thermal stress, with implications for resistance management under climate change scenarios.</p>