The woolly poplar aphidPhloeomyzus passeriniiSignoret (Aphididae: Phloeomyzinae) is a major pest of poplar plantations. We hypothesized that recent temperature increases may have contributed to the emergence and subsequent northward expansion of outbreaks in France. We rearedP. passeriniiat four temperatures to estimate its thermal requirements. We used experimental data to parametrize a mechanistic and temperature-driven physiologically-based demographic model. The model was used to simulate the effect of temperature on aphid dynamics and to assess the role of climate warming on the spatiotemporal dynamics of outbreaks. The lower developmental threshold was estimated at 6.4 degrees C and the development degree-days at 171. Our model supports the hypothesis that recent warming may have promoted outbreaks in northern France. During recent exceptionally warm years, more than 70% of the northern poplar area was favourable for outbreaks. Our model suggests that climate warming is not the sole factor involved. The dominance of resistant poplar genotypes such as 'Robusta' or 'Beaupre' may have preserved plantations from outbreaks before 1996 in southern France and until 2000 in the central part. Other factors, including biological characteristics, biotic interactions, or precipitation should be investigated.