Pest damage and diagnosis Symptoms of scale injury are very apparent in the spring, when the leaves are beginning to break bud. Delayed leaf expansion or early leaf drop on all or part of a tree are common symptoms. Look for groups of bumps or encrustations on twigs and trunks. If you can flip a bump off a twig with your thumbnail without disturbing the plant tissue below, then the bump is a scale, otherwise it is a gall.
Bumps produced by soft scales can be either smooth or cottony in texture.
Whereas, armored scales produce a waxy cover that varies in shape from circular to tear drop in shape. Armored scales do not produce honeydew. Note swollen reddish brown body of female and the shiny black mixture of honeydew and sooty mold on the leaf and twig . Note the brown oyster shape of the female cover, the extruded white waxy covering of the male, and the yellow crawlers that hatched from eggs. Above photo 1, Tuliptree scale, and below photo 2, Euonymus scale.