Scale insects come in many shapes and sizes, some more obvious than others. These insects are immobile, and will spend their adult life in one place. They cause damage by inserting mouthparts into the stem or leaf where they are located, and feed on the sap.
Scales can multiply rapidly, but will rarely kill its host plant. They will weaken a plant, leaving it susceptible to other insects or diseases.
Some scales will produce copious amounts of honeydew, a syrup-like substance that will coat the foliage and ground below. Black sooty mold, a fungus, will usually colonize the secreted honeydew. Seeing sooty mold is a good indicator of a scale infestation.
Treatment options will vary by scale type and host plant, but several options are available. Scales are usually found on shrubs, but some will attack trees, such as the tuliptree scale