|Hawk Moth on Leafy Spurge - natural predator|
Biological Control of Weeds
"The concept of classical biological control is very simple. Exotic (non-native) weeds are responsible for the vast majority of the range weed problems in North America. When foreign weeds are introduced, they come without the successful co-evolved enemies that are present in their native ranges. Without these natural checks present, the weeds are able to out-compete native vegetation. Introducing biological control agents can restore the natural checks and balances that control exotic weeds in their native habitats."*
*Integrated Weed Control - Bozeman, Mt
For leafy spurge on our ranch we introduced Leafy spurge stem borer (Oberea erythrocephala). They are a stem girdler that cause shoot death. The larvae develop in the stem and this will also cause shoot death. The larvae feeds in the crown as well as root tissue and diminishes roots.
We also introduced Leafy spurge flea beetles (aphthona spp:) The beetles develop in the roots. The experts think these will eventually cause big declines in spurge infestations. Larvae feed on root hairs and young roots, and compromise the plant's ability to take in water and nutrients. The adults feed on the foliage during the summer.