In part due to its vegetative strategy, western aspen is host to a large number of insects and diseases. However, only a few are agents of significant impact that can cause or warn of substantial changes in the condition of aspen clones. Environmental conditions, particularly drought stress, also play an integral role in the life cycle of the important insects and diseases of aspen, and regional droughts were the triggering factor in the initiation of the most notable instances of substantial aspen dieback and decline. This 58 minute webinar discusses some of the insect and disease problems.