Airplane dusting forest for western hemlock looper control. Pacific and Grays Counties, Washington.
Photo by: F.P. Keen Date: July 1931
Credit: USDA Forest Service, Pacific Northwest Region, State and Private Forestry, Forest Health Protection. Collection: Portland Station Collection; La Grande, Oregon. Image: BUR-8776
To learn more about this photo collection see: Wickman, B.E., Torgersen, T.R. and Furniss, M.M. 2002. Photographic images and history of forest insect investigations on the Pacific Slope, 1903-1953. Part 2. Oregon and Washington. American Entomologist, 48(3), p. 178-185
The following information about this control project was prepared by Malcolm M. Furniss and is taken from the Western Forest Insect Work Conference history page: www.wfiwc.org/history/photos/control
"Western Hemlock Looper. The first known record of extensive tree-killing by a forest insect in the western United States involved the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst).... A subsequent outbreak killed 200 million board feet (bd ft) of hemlock in Pacific and Grays Counties, Washington from 1929-1932. Losses in Pacific County were reduced in 1931 through the first airplane dusting experiment attempted against a forest defoliator in the western United States (Keen 1932). Keen was involved with the operation and voiced his concern in a letter to Craighead (13 July 1931) regarding toxicity of the calcium arsenate contained in the dust:
'In connection with the airplane dusting project, we are naturally experiencing some criticism from people who object to having poison scattered around in wholesale lots for fear of killing off the wildlife and even domestic animals. I have tried to get some information from the local Boards of Health as to what constitutes lethal doses of calcium arsenate for birds, mammals and humans but with very little success...'"