Scales are bark, branch, leaf, stem, and fruit pests. Hmm, that’s just about everything but the flower! These little pests can look like crusty and brown rounded bumps to white baggy cushions on your plants. They are like barnacles-and unless they have accumulated in numbers, they may be entirely missed.
Scales are “suckers” like aphids and mealy bugs. They are less mobile than the latter, however, and spend much of their lives in one spot. Their excrement is like the honeydew of aphids, and that sugary substance is an excellent growth medium for black sooty mold. If your plant has sooty mold or is crawling with ants (that like to feed on the honeydew), and you don’t have aphids, chances are you have an infestation.
Damage to your plant from scales is usually minimal unless there is a huge infestation but they can severely weaken your plant over time, in addition to making it look unattractive.
Scales have natural predators such as lacewing larvae, predaceous beetles and microscopic parasitic wasps, which all control the scale population. The beneficial wasp pierces the hard shell and lays eggs within the scale – thus the name parasitic. If you see a scale with a hole on its shell, it has already been attacked by one of these wasps.
But for most practical purposes, the easiest way to control scales is to spray the entire plant with a horticultural oil or apply a systemic insect spray. In the long run, if you keep your plants healthy with correct watering, fertilizers and mulching, they will be better equipped to combat any annoying insect.