Insect ecologist Richard Mason putting out a spray deposit card. Controlled field test of stabilized pyrethrins against the western hemlock looper. Mt. Baker National Forest, near Marblemount, Washington.

Photo by: R. DeWitz Date: July 10, 1969

Credit: USDA Forest Service, Pacific Northwest Region, State and Private Forestry, Forest Health Protection. Collection: Region 6, Forest Health Protection digital file collection; Regional Office, Portland Oregon.

For more, see: Mason, Richard R. 1970. Controlled field test of stabilized pyrethrins against the western hemlock looper. <a href="https://babel.hathitrust.org/cgi/pt?id=umn.31951d02995483v;view=1up;seq=1" rel="nofollow">babel.hathitrust.org/cgi/pt?id=umn.31951d02995483v;view=1...</a> Abstract: A new stabilized formulation of pyrethrins was field tested against larvae of the western hemlock looper by spraying from a helicopter. A selected number of larvae were placed in foliage on platforms were they were fully exposed to the spray and on small trees where they were partially screened from direct spray contact. Ninety-nine percent and 94 percent of the larvae on the platforms and on the trees, respectively, were paralyzed or killed by the insecticide. Most of the larvae fully exposed on the platforms were knocked down within a few minutes after spraying, whereas knockdown of larvae in the trees occurred over a considerably longer period of time. Recovery rate of paralyzed larvae was higher for those that were slow to be knocked down than for larvae knocked down quickly.

For additional historical forest entomology photos, stories, and resources see the Western Forest Insect Work Conference site: <a href="http://wfiwc.org/content/history-and-resources" rel="nofollow">wfiwc.org/content/history-and-resources</a>

Image provided by USDA Forest Service, Pacific Northwest Region, State and Private Forestry, Forest Health Protection: <a href="https://www.fs.usda.gov/main/r6/forest-grasslandhealth" rel="nofollow">www.fs.usda.gov/main/r6/forest-grasslandhealth</a>

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