|Biological agent type
Plant species attacked
Canada thistle (Cirsium arvense)
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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
Stem and root crown.
Mode of attack
The larvae mine the pith in the stems of bolting plants and may make them susceptible to opportunistic pathogens. The adults feed on leaves causing minor damage.
Collection and release information
This bio-agent is limited in distribution at this time. Consult with ODA for availability for your area.
History in Oregon
The crown weevil Ceutorhynchus litura was first introduced in 1981. It was reintroduced in 1988 and is now established in most eastern Oregon counties. The weevil is becoming more widespread but still difficult to collect. At numerous eastern Oregon sites plant densities of Canada thistle appears to be declining and the size of infested plants appear to be smaller.
Release status in Oregon
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