Similar to the European Praying Mantis, the Knapweed Root Weevil is also an exotic species. However, in this case it was introduced on purpose to help combat another exotic species — knapweed. Females lay their eggs on the top of the knapweed’s root crown. Once they hatch, the larvae burrow into the plant’s root, destroying the vascular root tissue and preventing the plant from transporting water and nutrients. Death of the plant can occur within two years. Research at Montana State University has shown up to a 99% reduction in knapweed density as a result of knapweed root weevil introduction. Go weevils!
Size: 20 mm long
Photo by: Glenn Marangelo on 10/7/21 in Missoula, MT