They feed on leaves of willowherb, water primroses and sallows. It was misidentified as great hairy willowherb in contemporary floras. Willowherb is a species of willowherb. Many of the small willowherb species are nuisance weeds in gardens. In Britain it is known as rosebay willowherb. Rosebay willowherb dominates much of the area. It is commonly known as the great willowherb, great hairy willowherb or hairy willowherb. Epilobium palustre is a species of willowherb known by the common name marsh willowherb. Epilobium alsinifolium is a species of willowherb known by the common name chickweed willowherb. The Rocky Mountain Willowherb ("Epilobium saximontanum") is sometimes included as yet another subspecies. It is also called "smallflower willowherb" in reference to its small size relatively. In the more open areas of the lower valley vegetation includes meadowsweet and great willowherb. Some species in the insect order lepidoptera frequently use the willowherb as its primary habitat.