Abstract. 1. Ongoing environmental change is predicted to have a strong impact on biodiversity. Studies have already noted a range shift in many species as they track their favoured environments. A key challenge entomologists are facing is to understand how insect pest species are responding to this rapid environmental change, and molecular ecology has a central role to play in this task. In the present paper, I argue that molecular ecology has much relevance in relation to the monitoring of insect pests of agricultural importance, with a focus on aphids.2. First, I examine how the combination of phylogeography and species distribution modelling can be a powerful approach to understanding species responses to climate change and to forecasting future distributions. Despite such a joint approach being increasingly used to understand these questions (e.g. in conservation biology), there are still very few studies that concern pest species of agricultural importance.3. I then discuss how the use of samples from natural history collections represent an opportunity to directly observe the evolution of species, enhancing our knowledge of the evolutionary processes occurring at ecological time scales. I introduce the Rothamsted Insect Survey (RIS) sample archive and the central role it plays in the studies of pest species of agricultural importance.4. Lastly, I assess how the advances in DNA sequencing technologies have allowed us to investigate genetic variation at the genome-wide level. Thus, they provide us with the opportunity of studying a variety of questions about the dynamics of pest insects that were previously impossible as well as unmanageable.