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Urophora solstitialis
Biological agent type
Seed head fly.
Plant species attacked
musk thistle (Carduus nutans)
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Urophora solstitialis adult
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
Mode of attack
The larvae cause galls in the seed heads that interfere with seed production and dissemination.
Destructive stage
Collection and release information
Agents have not been recovered at release sites and are not available at this time. 
History in Oregon
The seed head fly Urophora solstitialis was released in 1999 in Klamath and Malheur Counties and has not been recovered.
Release status in Oregon
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distribution map