Almost 100 years have passed since J.M. Swaine, the assistant entomologist in charge of Forest Insect Investigations, wrote, “Canadian bark-beetles: a preliminary classification, with an account of the habits and means of control”. The goal was to “put into the hands of practical foresters information of inestimable practical value… to prevent the continued loss of timber now being destroyed” by “the most insidious enemies of the forest”. In this paper, we celebrate Swaine’s pioneering work by summarising the foundational aspects of his early treatise of 1918: the “general habits” of bark beetles, classifications of their behaviour, causes of population increase, and mitigation tactics. In the founding text, Swaine identified all major Dendroctonus Erichson (Coleoptera: Curculionidae) bark beetles found in Canada, although details on life histories were scarce. We summarise current knowledge of the life histories and population dynamics of the spruce beetle, D. rufipennis Kirby; the Douglas-fir beetle, D. pseudotsugae Hopkins; the eastern larch beetle, D. simplex; and address the current range expansion of mountain pine beetle, D. ponderosae Hopkins. We review how aspects of global change, such as invasive species, have altered the population dynamics of certain bark beetles. Finally, we conclude with lessons from two of the many past contributors to bark beetle ecology in Canada, J.M. Swaine and H.A. Richmond.