Hi, I have a starfruit tree I am growing in a greenhouse. It is covered in these tiny red dots, almost like sand. It won't come off if a spray it, but I can rub them off. The entire tree is covered. The underside of all the leaves and the branches. I thought it might be spider mites, but I don't think that's what it is. I've looked at it under a microscope and it didn't look like anything....a ball of poop if anything. I've seen spider Mites under a microscope before. Was hoping someone might know what it is. I've attached a picture.