It seems like Japanese Beetles love Zinnias as much as I do. Every year that I grow zinnias they show up in bulk on them, leaving the leaves full of holes. The good news is, at this stage the beetles are easily taken care of.
All you need is some soapy water and a pair of gloves (if you are like me and not interested in touching them with your bare hands). Just pluck the beetles right off the plant and plunk them in water and dish soap mixed. Dish soap dissolves insect exoskeleton causing death. It’s not harmful to anything other than the beetle you’re plunking in.
I applied this treatment to one of my zinnias yesterday, and figured I share this easy pest solution.
Meneely Family Nursery 