By the time you see that kind of webbing, it is a serious infestation. They are extremely tiny and you need good vision -- or 60x to 100x magnification in case of tomato russet mites (but we're not talking about them here) -- to see them at all. One often suggested way to check for them is to hold a white paper under the leaf, tap the leaf and see if you see red, brown, or black "powder" if you can smear the powder into streaks by putting the paper on a flat surface rubbing the paper firmly with your finger, then that's a definite yes.
If you want to start by just rinsing the plant with water under a shower or outside garden hose, or kitchen sink spray, by all means. I had two spotted mite infestation and used sudsy Dr. Bronner's liquid soap water in a big-gulp cup to dip and dunk the leaves in -- AMAZING number of specs were swirling around in the liquid after just one good dunk. That's when I KNEW I was in trouble. Until then, I had underestimated the degree of infestation because I simply could not see the mites.
I have to tell you, though, that plain water didn't dislodge the mites very well at all and after a thorough shower with whet seemed like a pretty strong water pressure, I was still seeing a lot of mites float off when I tried the cup-dunking in soapy water afterwards.
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