Published online by Cambridge University Press: 12 June 2017
The use of insects in the biological control of weeds necessitates that these insects have very restricted host ranges. Specialized insects boring in stems or living in seed pods have adaptations which obligate them to their host plant. However, the leaf-feeding beetle, Chrysolina quadrigemina Suffrian, imported for the control of St. Johnswort (Klamath weed) (Hypericum perforatum L.) through its feeding habits, tropistic responses and synchronization of its life history to the growth phases of the plant has shown that it is restricted to its preferred host plant.