Eeeekkkkk!!

Whiteflies.

Silky threads and cocoons sounds like either spiders or caterpillars. Spray an insecticide on both sides of the leaves.

If it is some kind of mildew/fungus then a fungicide would be the thing to use.

NEEM oil will treat both insects and fungus outbreaks.

On closer inspection of the top leaves socalgal might have a point - it looks like you may have a whitefly on the first photo - not sure about the larvae in the second photo as usually whiteflies are on the underside of the leaf. Disregard that - I see that the second photo is the UNDERSIDE. So it could very well be whiteflies after all.

The fibers could be some fungal outbreak from honeydew of the chewing insects. We get black sooty mold on crepe myrtle leaves here if aphids become a serious infestation - the sooty mold is not serious but unsightly.

I hope you don't have giant whiteflies - they look pretty scary!

http://cekern.ucanr.edu/Entomology/Newsletters_and_Other_Entomology_Information_114/Whiteflies/

http://ipm.ucanr.edu/PMG/PESTNOTES/pn7400.html