Predicting future risks of damage by insect pests is an important aspect of forest management. Climate change has the potential to affect forest pests and their impact on trees through higher temperatures, altered precipitation patterns, and more frequent extreme weather events. Warmer temperatures are likely to have complex effects on insects, influencing, among other things, development rate and the seasonal timing of life-cycle events, while also affecting their host trees and natural enemies. It is not possible to predict the future impact of forest pests with any precision, but some generalisations can be made based on the ecological characteristics of different insect types. The damage caused by aphids and related insects is likely to increase as the climate warms. Higher temperatures will increase their reproductive rate, and drought stress of host trees may increase their susceptibility to aphid attack. The impact of bark beetles and related insects is also likely to increase, due to factors such as increased frequency of windblows, drought stress of host trees and, for some species, a shorter generation time. Effects upon defoliators are more difficult to predict, but the abundance and impact of some species is likely to be influenced by an increase in the number of generations per year and changes in their geographical distribution. Changes in forest management as a response to climate change, such as the introduction of new tree species, could additionally lead to the emergence of new pests.