Around 1800, large swathes of the Harz were deforested. The less resistant spruce monoculture, that arose as a consequence of the mining industry in the Upper Harz, was largely destroyed by a bark beetle outbreak and a storm of hurricane proportions in November 1800. This largest known bark beetle infestation in the Harz was known as the Große Wurmtrocknis, and destroyed about of spruce forest and lasted about for 20 years. The woods were largely reforested with spruce. Continuous problems with bark beetle and storms were the negative side effects of mining in the Harz Mountains.