Most insect resistant flowers
Thanks for writing. It really depends on what pests are the most problematic --- as each insect has its own set of preferences. If it's grasshoppers, for example, I don't know of any plants that have good resistance (grasshoppers have been known to chew up window screens!).
If Japanese beetles are a major problem, check out this list of plants they typically leave alone:
---Justin, Senior Garden Editor, BHG.com