spider mites. Get a magnifying glass and you can see them. The remedy is gentle dish soap. Like Dawn or ivory. Many soaps have degreasers and will hurt the plant. Add a tablespoon to a half gallon and spry the infected area. Do it again in 6 days then again in 6 more days. eggs linger. Sequester all affected plants and spray any that are suspicious. Be on vigilant watch for a month of no new bugs. I remove most affected leaves but not necessary. Aggressive behavior on your part is necessary. No need for the high price poison solutions. The soap is better and safer.