Visible mealy bugs are actually female soft scale insects covered with white waxy threads, making them hard to control with chemical treatments. They are occur worldwide in area with a moist and warm climate and are considered a pest as they infest a wide range of vegetable, ornamental and fruit crops where they feed on plant sap.
Mealy bugs produce a fluffy white wax on the stems and leaf nodes. They also suck plant sap. The excess of sugars they absorb is excreted as honeydew, making the leaves, stems and fruits sticky. Sooty mold can grow on honeydew giving the surfaces a blackened appearance and affecting photosynthesis. Sticky and fouled plants and fruits are unmarketable. Severe infestations will reduce plant health and growth, and can result in wilting.
Mealy bugs are sexual dimorphic, meaning the appearance of males is completely different to that of females. Males are tiny wasp like flying insects and are rarely seen in the crop. Female mealy bugs tend to live together in clusters in protected parts of plants, such as leaf axils and under loose bark. They are covered with a white waxy secretion. A female can lay 300 to 500 eggs in a cotton-like pouch. After laying eggs, which takes 5-10 days, the female mealy bug dies. The young bugs, which are most mobile, disperse to find suitable feeding sites. There are 3 nymphal stages. The length of the lifecycle depends on temperature and takes 90 days at 18°C and 30 days at 30°C.
Several species of mealy bugs are known: the citrus mealy bug (Planococcus citri), the obscure mealy bug (Pseudococcus affinis) and the long-tailed mealy bug (Pseudococcus longispinus)