Canada Thistle

These insects are much more effective in combination. Each insect stresses the plant in a different way. The insects do not compete with each other but act together to reduce thistle competitive fitness.

Tortoise beetle

Cassida rubiginosa: The larvae and adults of this beetle feed on the stems and foliage of Canada and musk thistle. Overwintering adults begin feeding and laying eggs in early spring. Feeding is continuous until well after the first frost. Plants are often severely defoliated by this hardy and effective beetle.
$90 per release.

Canada thistle stem mining weevil (Ceutorhynchus litura)

Stem mining weevil

Ceutorhynchus litura: The larvae of this hardy weevil hatch on young leaf or stem tissue. They bore into the plant and mine towards the main stem. Older larvae mine the stem, crown, and root. The plant's root reserves are reduced by an average of 50% in attacked plants. Canadian research showed that the incidence of a fatal rust fungus disease was more than doubled when the insect is present.
$125 per release.

Stem gall fly

Urophora cardui: This fly lays eggs into stem tissue. The larvae then cause the formation of a hard woody gall that robs the plant of energy. Stems above the galls are often malformed, stunted and dry up before unattacked stems.
$90 per release.

Integrated Weed Control
4027 Bridger Canyon Road
Bozeman, MT 59715-8433

Toll Free: 1- 888-319-1632
FAX: 1-406-587-1989
E-mail: iwc@integratedweedcontrol.com

Photographs courtesy of Integrated Weed Control, USDA ARS, APHIS Bozeman Bio-control Station, and Agriculture Canada.

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Bozeman, Montana