Answer: In answer to where they came from, it is quite possible they came in with your plants but the population was so low you didn't notice it at first or perhaps they came in through a window screen or who knows how -- pests have an amazing ability to travel. Unfortunately, based on your description I am not quite sure which pest you are facing here, so I will make an overall suggestion and hope it works for you. Try washing the plants under a strong stream of water (a kitchen sink sprayer works well) about twice a week for several weeks. If the pests are aphids or spider mites this should do the trick. If the problem does not disappear with that treatment, try insecticidal soap according to the label instructions. (It can be used on edible plants, but do read the label and of course wash the leaves before you eat them as you normally should).
Q&A Library Searching Tips