Question
I have knock out roses and gray specks appear on the leaves as if someone has splashed paint on them . Then something eats the leaves leaving only the veins . Any ideas ?

Answer
Saw flies or rose slugs are what are doing the damage. This insect or tiny looking slug, eats from the undersides of the rose leaves. This leaves only a paper thin layer on the top. Then this tissue falls away because it is dead and only the veins are left so the leaves look like a lace tablecloth. Sometimes blasting water on the rose bush washes them off but if it  is a bad infestation you will need a rose insecticide such as Orthos Rosepride Insecticide. Make sure you also spray all around the base of the rose bush as that is where many will be hiding.