Development of the Problem 



Magdalis gentilis LeC. belongs to a group of small black or blue weevils, the 

 larvae and adults of which feed on the foliage or shoots of pine in many forests of 

 the United States and Canada, as well as of other countries. Most species of Magdalis 

 breed in slash, or in dead and dying portions of standing trees; accordingly, they are 

 not particularly troublesome. However, some species are significant pests of young 

 pine stands. 



Until the mid-1960's, there were no records that any species of Magdalis had 

 caused any significant amount of damage in the northern Rocky Mountain region. The 

 known collections made since the weevil was first reported in the northern Rockies in 

 1923 have been scattered and infrequent, as shown in the following tabulation: 



Species Locality Year 



M. gentilis LeC. Glacier National Park, Montana 1923 



M. lecontei Horn New Meadows, Idaho 1929 



M. imhellis (LeC.) Coeur d'Alene, Idaho 1932 



M. lecontei Horn Setters, Idaho 1963 



In 1965, a rather severe infestation of M. gentilis was detected on an 18-acre 

 tract of lodgepole pine regeneration on the Lewis 5 Clark National Forest in west- 

 central Montana. This site had supported a 150-year-old stand of lodgepole pine which 

 had been clearcut in July of 1954. The logging residue was dozer-piled in October and 

 was burned in November of that year. Lodgepole pine regenerated naturally; between 

 June 1 and 10, 1965, the young overstocked stand was thinned.^ Early in August, 

 foresters working in the area noticed that foliage on many of the crop trees was dis- 

 colored. I examined the trees late in August and found numerous M. gentilis adults 

 feeding on the needles (Fellin and Schmidt 1966). 



Since this discovery in 1965, I have observed several other instances of M. 

 gentilis damage to lodgepole pine regeneration on the Lewis 5 Clark National Forest. 

 In all instances, weevils appeared in stands that had regenerated naturally following 

 clearcutting and then had been precommercial ly thinned. 



"^The forest management practices on this site are typical of those being used over 

 extensive areas of lodgepole pine on the Lewis S Clark National Forest {?ig. 2). 



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