Insect geographical limits are tied to their ability to tolerate thermal extremes. Climate change is increasing both mean global temperatures and extreme weather event occurrences, which has implications for shifting habitats. This is not only making climates unsuitable for native species but also opening habitats for new species to invade. Mountain Pine Beetles (Dendroctonus Ponderosae; MPB) are a species of bark beetle that have expanded past their native range in the westernmost part of north America, severely impacting the forests of British Colombia and Alberta, and continuing to expand eastward. As a freeze-avoidant insect, MPB have the capacity to lower their internal freezing temperature and survive extreme cold through cryoprotectant accumulation and maintenance of ion balance, but whether they have an active transcriptional response to a cold snap, and if these changes carry over into translated proteins is unknown. We performed whole animal RNA-seq on MPB that had previously undergone a polar vortex event. Overwintering beetle larvae were cooled to temperatures ranging from 5°C to -15°C. Proteomics were completed using the same samples from which RNA seq results were obtained. We identified a clear temperature trigger for a transcriptional response to cold at -15°C, where transcription is upregulated in genes related to ion balance and membrane development. These same genes also appear as proteins present in our proteomics data, meaning there is a further response to cold at the translational level. Overall, our results show that mountain pine beetles respond actively to very low temperatures.