Dragonfly:
Without a picture or sample it is going to be a little more
difficult. Sounds like spider mites due to the webing that can also effect bloom cycles.No need to burn anything that
was dismissed 20 years ago.Spray it then cut it back so your not dropping mites on to other plants.It would be a good idea to get a soil test done to see where your N-P-K
is. If you can find insecticidal Soap w/Sea Weed in it
I have used that to kill off the little pest. You may
want to treat the backside to see if the Hibiscus has
a bad reaction to the soap. Sometime they do.
Art

I have put up several far and close up pictures. It looks like I might have more than one problem, after looking at it with a magnifying glass. I saw a tiny black spider, and a bigger longish brown bug. When I came in, I found a larger light grey or light brown spider running down my arm (I brushed it off so fast, I'm not sure of the color!); I was around but not touching the hibiscus, but was cutting off spent rose blooms, and near my orange trees, too. (And it is a double red, not single.) Please look at the link below for some good pictures of it.

Here is a link that might be useful: My Problem Hibiscus

I also have a problem with a hibiscus tree I just bought from Lowe's. It looked great for a week or two, and then we had a really big rain and the leaves started wilting, and before I knew it, they all fell off and there is nothing left to the tree. I realized the pot that the tree is planted in did not have any drain holes, so we immediately drilled holes in the bottom of the pot, and replaced the soil in case it was mildewed. It has been about 2 weeks since then, and the treee is still not coming back, even though it has gotten plenty of water and sun. I don't think it's completely dead because when I scratch beneath the surface, I see green. I don't know what else to do.