Experts and BHG readers answer.
Hi, Well it depends on what kind of bug you have. Because these plants are highly attractive to good bugs such as butterflies and bees, I don't recommend using a general purpose insecticide on them. If, however, you see an outbreak of a particular type of pest, you could try spraying the plant with some Insecticidal Soap, which isn't as pervasive as standard insecticides, but does a good job on things like aphids. AGain, it will be difficult to control problems with coneflowers, simply because all insects love this plant, both good and bad.