The scale insect is a very small insect that feeds on plant sap by piercing young leaves and stems.

It belongs to several groups that can look very different from one another. Based on their outer covering, they can be divided into three types:

• the armored scale insect, so called because its soft body is protected by a gray-white waxy shield;

• the cottony or mealy scale insect, which has a soft body protected by white wax filaments;

• the type with a hardened body, because it is completely impregnated with wax.

Scale insects attack most ornamental plants, especially succulents. They also like conifers, vines, and citrus plants.

Males have wings, while females do not, and after laying eggs they sometimes even lose their legs, remaining motionless and attached to the plant.

They feed on sap to obtain proteins and discard all the sugars, producing honeydew, a sugary substance that can cause the fungal disease called sooty mold and attract other insects, such as ants, which feed on it. As with aphids, ants often form a protective relationship with scale insects and carry them from one plant to another to ensure that honeydew production continues.