The mountain pine beetle epidemic is considered to be the largest forest insect blight in North American history. In the past, the pine beetles played a humble role, attacking old or weakened trees, making room for new healthy trees. The changing climate has turned their seemingly benign role into something much more deadly. An explosion in pine beetle size and numbers has forced them to turn their attention to healthy trees. Furthermore, they are reproducing twice as much as normal. Once thought to only produce one generation of tree-killing offspring per year, new research now shows that some populations are producing two generations per year, potentially increasing overall population by 60 times.