BIOLOGY: Adults are small, brown weevils 3-4 mm long with a rounded body.  Larvae are small and found inside Canada thistle stems.  Overwintering adults lay eggs on the ground in early spring.  Larvae enter stems in early May, feed through July, pupate and emerge as adults in late summer.

DESTRUCTIVE STAGE: Larvae (stem feeding)

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.