I always see some spider mites on various plants when they come inside for winter. Some plants get them every winter. Crotons are notorious for their appeal to SM's. Hosing the foliage when watering plants can help keep them at bay. If you are using a soap, please make sure it's safe for plants. They make insecticidal soap for this that does not have harsh detergents which can damage some plants. I don't use anything but showers of plain water unless that does not seem to be enough, in which case leaves can be wiped (top and bottom) with a cotton ball damp with rubbing alcohol. This will physically remove the mites, and cleans leaves. If a plant has too many leaves to wipe individually, misting with alcohol can also help keep them at bay until the weather changes.
