Langford, G.S. 1926 The life history of the willow scale (Chionaspis salicis-nigrae Walsh).. Circular of the Colorado State Entomologist 51: 50-58.
Langford, G.S. 1926 The life history of the willow scale (Chionaspis salicis-nigrae Walsh).. Circular of the Colorado State Entomologist 51: 50-58.