In a dynamic world, organisms must swiftly adapt to environmental changes. Phenotypic plasticity enables organisms to alter their traits within their lifetime, providing a rapid response to shifting environments. Dung beetle horns display extreme plasticity, with males exhibiting varying horn sizes (horned "major" to hornless "minor" morphs) based on larval diet (dung type). Horns are utilized in male-male contests for mating, and body and horn size strongly influence success. Though plastic responses to dung quality are well studied, the interplay of temperature and nutritional conditions on these traits remains unexplored. We reared the dung beetle Digitonthophagus gazella in bison (Bison bison) and cattle (Bos taurus) dung, and across seven temperatures (22-34°C) to determine how these environmental factors interact to shape plastic responses in body size and horn length in dung beetles. Almost all (99%) of reared male beetles were major males in both cattle and bison dung treatments, indicating that both dung types are high quality resources for developing dung beetle larvae. The interaction between dung quality and temperature revealed distinct responses: beetles from bison dung show no temperature related changes in body size and horns, while those from cattle dung exhibit larger sizes at intermediate (26-30°C) temperatures compared to those at colder (22-24°C) or warmer (32-34°C) temperatures. This suggests that cattle dung may be a higher quality resource for D. gazella, allowing beetles to utilize a thermal optimum. In addition, development rates increased with temperature, with a more pronounced increase in the bison dung treatment. The interactive effects of diet quality and temperature on morphological and physiological plasticity in dung beetles demonstrate that plastic responses to one factor are not always fixed and can vary with changes in another. To accurately predict how organisms will respond to changing climates, it is essential to evaluate how thermal responses are altered by other factors such as diet quality.