Several species of mealy bugs are known to appear in greenhouses. The most important ones are the citrus mealy bug (Planococcus citri) and some Pseudococcus-species. The citrus mealy bug can be found sporadically in cucumber, melon and aubergine. In tomato Pseudococcus affinis has become more and more widespread.

The bugs are covered with a white waxy secretion. A female can lay 300 to 500 eggs in a cotton-like pouch made of wax threads. 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 and then begin to feed on plant sap. There are 3 nymphal stages in the mealy bug's lifecycle. The length of the lifecycle depends on temperature and takes 90 days at 18°C and 30 days at 30°C.