It sounds like you have spider mites. The pest itself is microscopic, so it is the resulting damage that alerts you to their presence. Spider mites suck the chlorophyll out of plant leaves causing the foliage to dry up and turn yellow. The leaves become stippled with tiny, light colored dots. Each of these dots represents entire areas of the leaf's tissue that has been destroyed by the mites. Affected leaves feel like sandpaper, the texture is rough to the touch. Often you will find a fine webbing in and around the plant leaves.

If possible, affected plants should be removed as soon as possible, isolated, if not quarantined, from your other plants. I had success treating my plants with a spraying routine alternating hot pepper spray and insecticidal soap. You can find both of these products at most local garden centers. I first sprayed with the hot pepper, then about 7 days later I sprayed with the insecticidal soap and then the following week sprayed the hot pepper again. It helped that we had a few good rains, as spider mites hate the rain. I saturated the undersides of the leaves thoroughly because that is where the pests reside. Now, even though this method of insect control is earth friendly, I never do a wholesale spraying of my garden. Instead, I spray strictly in isolated areas where the problems persist. And I only spray in the early morning, when my plants are full hydrated.