Webbing on a plant is either a warning or good news, and telling them apart takes one look. Fine, shapeless silk over the leaves and shoots, with the upper side of the leaves finely mottled pale, is spider mite, and it means numbers are already high: the webbing comes after the stippling, not before it. A web with structure (a wheel, a sheet or a tangle) with a spider sitting in it is a spider, and UC IPM counts spiders as mostly beneficial because they eat pest insects.
The rest of what gets called “webbing on plants”. Some are pests we have not profiled yet; some are insects doing you a favour; some are not insects at all, and no treatment will help.
A web with structure (a wheel, a sheet or a tangle) with a spider in it, and no stippling on the leaves unless mites are there too. Spiders eat insects, not the plant, and UC IPM counts them as mostly beneficial. Leave them where they are.
Garden spiders →Fluffy white wax in the leaf axils, leaf sheaths and joints where stems and leaves touch, not a silk web. Pull it apart and the soft, oval, segmented insects or their eggs are underneath, and the leaves below are often sticky with honeydew.
Citrus mealybug →Not an insect. White or yellow mould-like growth of soil fungi on the compost surface or on decaying plant matter; they live on dead organic matter, not on the plant. They thrive where compost stays wet and full of decaying material, which suits fungus gnats too, so water less and make sure the pot drains.
Four questions about the damage separate these better than an appearance can, and this page answers some of them for you.