Butterfly bush problem
In general butterfly bush is adaptable to a wide variety of conditions. However, they require well draining soil or can be susceptible to root rots. They also benefit from they benefit from a 2- to 3-inch layer of organic mulch. Once established they are fairly drought tolerant. Make sure the soil is well drained.
They can also be susceptible to spider mites, a sucking insect pest. Look at our website for photos. http://extension.umd.edu/hgic/spider-mites-flowers-and-groundcovers
If this seems to be the problem you can contact your extension for control information http://www.ipm.ucdavis.edu/IPMPROJECT/contact.html