You haven't tried to remove one of those " slugs, have you? :-) If or when you do, you'll find that they are actually a part of the actual plant....which is infected with a disease called Asters Yellows.

No, I didn't want to touch them! Thanks for the info. What do I do about it?

(I've searched for other info on asters yellow but the photos don't look like mine.)

This type of flower mutation is not uncommon with Rudbeckia. Aster Yellows can take on many characteristics. There is nothing you can do, other than remove and destroy all of the affected plants asap. The phytoplasma (virus-like) organism is spread by leaf hoppers. Once a plant becomes infected, there is no cure.

Truly, you'd learn something if you picked on of those flower heads and examined it. You would see, clearly, that it is simply extremely distorted.

Here is a link that might be useful: Click here for more pictures like yours.

Thanks for all the information & photos! Yes, those look just like our flowers & disease.

We did look at them more closely, especially after realizing those worms didn't move!

There is nothing you can do, other than remove and destroy all of the affected plants asap.

==>>> you did not acknowledge what rhiz said!!!!!

are the plants gone yet???

ken

Yes, of course, we got rid of the diseased plants.

It IS creepy looking, isn't it? It's easy to see why you mistook it for something that was devouring your plants. Thanks for posting such good pictures...you've probably helped someone else with your question.