I have checked your page regarding petunias but was unable to determine what I might be dealing with. I have noted that some of my petunias develop “sticky” stems and leaves. Afterwards they start to wilt and eventually die. Is this related to one of the problems listed on your page, or am I dealing with another problem? I would sure like to determine what causes this as I have lost lots of petunias when this happens.
I can't determine which pest, but you can treat the plants to take care of them.
Neem Oil is a good treatment. Neem Oil is organic and safe for people, pets and bees.
Here are some links with more information.