Photoperiod modifies thermal reaction norms for growth and development in the red poplar leaf beetle Chrysomela populi (Coleoptera: Chrysomelidae)

► Thermal reaction norms for growth and development are affected by photoperiod. ► Growth and development are faster under short day at low temperatures. ► Growth and development are also faster under long day at high temperatures. ► Adults are heavier on average under short day at low temperatures. ► There is virtually no effect of temperature on body weight under long day.