Temperate deciduous forests are key contributors to the global carbon sink due to their carbon sequestration capabilities, which is significantly attributed to soil respiration (Rs). However, the Rs response to disturbances such as insect infestations, which are expected to increase as the climate warms, remains unclear on the seasonal and diurnal scales. In 2021, eastern North America suffered a record-breaking defoliation from a spongy moth (Lymantria dispar dispar) infestation. Here, we used automatic closed dynamic soil chambers to assess the seasonal and diurnal Rs patterns in a >90 year old oak-dominant temperate forest in Canada’s Great Lakes region. Rs was measured over the growing seasons (GS) from April to October of 2014-2023. High-frequency Rs measurements followed seasonal patterns of soil temperature (Ts) but showed strong seasonal and diurnal Rs-Ts hysteresis. The late GS showed greater Rs than the early to mid-GS, despite similar Ts over the full study period. Diurnally, the Rs-Ts pattern showed strong hysteresis over the full GS, with figure-eight loops in the beginning and end of the GS, and counter-clockwise in the mid-GS. Pre-infestation, the observed Rs-Ts hysteresis loops were counter-clockwise for the entire GS, with Rs continuing to increase later in the day (1800-2300h) despite consistent high Ts. Post-infestation figure-eight loops during high heterotrophic respiration indicate a midday late-GS physiological increase not seen pre-infestation. This work shows that infestation lowered the overall Rs and altered diurnal Rs–Ts relationships. This highlights the need to include sub-daily, disturbance-driven Rs dynamics in forest carbon models.