I think you should learn as much as you can about Spider Mites. Spider Mites cause a lot of damage to my trees and usually I do not see them until the tree starts to decline in health. Ryan Neil from Bonsai Mirai has a nice long video out titled “Spider Mites Identification“. I highly recommend that you watch this great video and learn about the little rascals. I have added the video to the Diseases/Insects page under Bonsai Basics. Thumbnail photo courtesy of BugGuide.