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Larinus obtusus
Biological agent type
flower weevil
 
Plant species attacked
diffuse knapweed (Centaurea diffusa)
spotted knapweed (Centaurea stoebe)
meadow knapweed (Centaurea pratensis)
 
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Larinus obtusus adult
 
Larinus obtusus emerging
Images by Eric Coombs, Oregon Department of Agriculture.

 
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
 
Site of attack
Leaves and seeds.
 
Mode of attack
Larvae consume the seeds and adults can defoliate plants when in large numbers.
 
Destructive stage
Larval and adult.
 
Collection and release information
Distribution is widespread, weevils can be collected using a sweep net during June and July. Consult with ODA for availability in your area.
 
History in Oregon
The seed head weevils Larinus obtusus and Larinus minutus were recovered in Hood River and Douglas Counties on meadow knapweed for the first time in Oregon. Larinus obtusus shows a distinct preference for the larger and earlier available seed heads of meadow knapweed. Several adults can be produced in a single seed head. Adult weevils emerging from Meadow knapweed are significantly larger than from diffuse and spotted knapweeds.
 
Release status in Oregon
 
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distribution map