Hoff , R. J. 1 989. Differential susceptibility of ponderosa pine to the gouty pitch midge 

 (Cecidomyia piniinopis). Res. Pap. INT-399. Ogden, UT: U.S. Department of 

 Agriculture, Forest Service, Intermountain Research Station. 4 p. 



In 1985, 14-year-old ponderosa pine in a provenance test in northern Idaho were 

 severely damaged by the gouty pitch midge. Dead or dying tips varied from to 85 

 percent for individual trees, and to 17 percent for provenances. The most resistant 

 provenances came from seed collected in northernmost Idaho and northwestern 

 Montana where the midge is more abundant than in the southern portions of the study 

 area, comprising central Washington, the northern slopes of the Salmon River, and the 

 Bitterroot River of Montana. Resistance to the midge apparently is an inherited trait 

 influenced by degree of exposure of parent trees. 



KEYWORDS: insect resistance, pest resistance, seed source 



