BIOLOGY: Adults are 4-5 mm and have large zebra striped wings. Larvae are C shaped and found inside Canada thistle stems. Overwintering larvae form large had galls on stems. Adults lay eggs in stems in early summer. Larvae feed through the winter inside stems.
DESTRUCTIVE STAGE: Larvae (stem gall forming)
IMPACT TO HOST: Larvae mine into stems causing damage to plants. They are also known to introduce secondary pests such as fungi and pathogens. Stem mining weevils are best when used in combination with additional biocontrol agents.
REDISTRIBUTION: Difficult to collect. Available through purchase from commercial biocontrol vendors.
- SCIENTIFIC NAME: Urophora cardui
- COMMON NAME: Canada thistle gall fly
- TYPE OF AGENT:
- GENERATIONS PER YEAR: One
- OVERWINTERING STAGE: Larvae (in stems)