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Bull thistle
BULL THISTLE (Cirsium vulgare )
Urophora stylata, a fly predator, is used to help control this thistle. The female fly lays eggs in the seed head of the thistle. The maggot then consumes the seed in the flower. This species has overwintered in Colorado but the limited numbers will not allow for general redistribution.
Bull thistle |
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Urophora stylata |
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Photos by: Eric Coombs, Oregon Department of Agriculture; L.L. Berry, bugwood.org; and Peter Harris, Agriculture and Agri-Food Canada, bugwood.org
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