mealybug, common name for certain unarmored scale insects that exude a granular white secretion, giving them a mealy appearance. Many are common greenhouse and crop pests. Adult females are wingless, with oval, segmented bodies and well-developed legs. The females and young feed on various parts of plants with their sucking mouthparts. Adult males have no mouthparts and do not feed. In egg-laying species the female produces several hundred eggs in a mass covered with waxy threads. In other species the young are born alive. The most serious pests are mealybugs that feed on citrus; other species damage sugarcane, grapes, pineapple, coffee trees, ferns, and orchids. Mealybugs are classified in the phylum Arthropoda, class Insecta, order Homoptera, family Pseudococcidae.