The oval, flat body of the female is wingless, distinctly segmented and about 3 mm (0.12 inch) in length. Waxy secretions make it look as if it is covered with flour - they also form a fringe of long filaments. The winged males appear about 4.5 mm (0.17 inch) long due to their tail filaments.
Citrus mealybugs live on all aerial parts of the host plant. They reduce its vigour by extracting plant sap, and they produce copious amounts of honeydew, which covers surfaces beneath the feeding sites and enables the growth of sooty mould. Extensive sucking on fruits may damage them directly, e.g. by causing them to tear. In the case of heavy infestation, white, fluffy masses consisting of wax secretions are found sticking to all plant parts. In severe cases, the sap loss seriously affects the health of the plant: leaves become chlorotic and distorted, or even wilt and fall off, and fruits are dropped. Occasionally, growth will be stunted or parts of the plant will die off. The damage is normally most pronounced during the dry season.
Each female of Planococcus citri lays up to 600 eggs into an egg sac, which it deposits anywhere on the plant and then protects with fluffy white tufts of wax filaments. After 1-3 weeks, the first instar larvae hatch. These „crawlers“ are very active and quickly disperse over the plant in search of a suitable feeding site. After passing through two more instars, the female larva will molt towards an adult; the male, however, will form a pupa, from which it emerges a few days later. Unlike scale insects, the mealybug females stay mobile and can therefore spread themselves. The winged males are rarely seen, as they are very short-lived: they fly mainly during the early morning and are attracted to the females by a sex pheromone.
Depending on the climatic conditions, there can be many generations per year, and all development stages are usually found side-by-side at any time. Like other mealybugs, P. citri is frequently attended to, and transported by ants.