Explanation of Names
Urophora cardui (Linnaeus 1758)
native to central and southern Europe; introduced to North America for weed control(1)
One to thirty eggs are laid in stems during plant's growing season. Overwinters in the third instar, mature larva, within a stem gall on Canada thistle. Pupates in early spring.
Release has been approved by the Animal and Plant Health Inspection service (Canada). It is no threat to non target species. Thistle is reduced by as much as 48% and grasses and forbs return to previously infested areas.