Zimmerman Pine Moth is one of the most common bugs I treat for in the Fort Collins area. Most commonly a pest of Austrian pine, they eat the wood around branch junctions causing weakness and leading to breakage. Treatments can be done in early spring or late summer. Sufficient water reduces the incidence of Zimmerman Pine Moth and can also help the tree recover from damage faster.
Although you might think this would be caused by wind or snow loads, it was actually brought about by extensive Zimmerman Pine Moth damage.