Mealybugs and scales
recognizable as insects. The females are wingless and immobile, and covered with a hard scale (armoured scales and soft scales) or with waxy threads (mealybugs) [...] species extract their nourishment from roots, whilst others are gall-formers. A few species can also transmit harmful viruses. Mealybugs inflict damage on [...] presence of mealybugs is sufficient to render the product unfit for sale. A very small population can thus cause considerable loss of value. Soft scales