<p> Most studies examining effects of extreme temperature on insect immunity have focused on negative impacts of high-temperature exposure. Although largely unexplored, a recent study suggests that repeated exposure to freezing temperature may enhance insects&rsquo; ability to survive microbial challenge. To determine if repeated low-temperature exposure impacts innate immunity of the goldenrod gall fly, <i>Eurosta solidaginis</i>, we counted hemocyte number, measured phenoloxidase activity and assessed antibacterial activity, and I examined up-regulation of immune-related genes in winter-acclimated larvae 24 h or 96 h after they were subjected to either zero (control), five, or ten diurnal exposures to -18&deg;C. To assess if time spent frozen, rather than freezing and thawing, influenced immunity, we also counted examined immune factors in larvae exposed to a single, six-day constant freeze. Repeated freezing negatively impacts hemocyte number, antimicrobial activity against Gram-negative bacteria, and had varied effects on phenoloxidase activity in the goldenrod gall fly. I suggest the effects of repeated cold exposure on insect immunity are governed by energy trade-offs and are not likely to mimic the effects of a single freeze.</p><p>