Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Sternorrhyncha
Superfamily: Coccoidea
Family: Pseudococcidae

Mealybugs are small, unarmored scale insects that are covered with a white mealy coating; some have white hairs attached to their bodies. They are found in moist, warm climates all around the world. Many species are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees and also act as a vector for several plant diseases. They feed by sucking on the plant sap. They excrete honeydew which is a sticky substance that some other insects feed on. Ants, bees and wasps feed on the honeydew. Bees feeding on honeydew excreted by planthoppers feeding on the sap of Coriaria arborea (Tutu) produce toxic honey. Mealybugs like the presence of ants because the ants protect them from predators and parasites.

With high humidity and mild temperatures, mealybugs produce a batch of young every two to three weeks. Heavy infestations can occur on the Daphne species, Cordyline species, Yarrow, Grapes, Succulents, Coleus, Hibiscus, Ferns, Orchids, Citrus, Begonia, Polyanthus, Liliums, Calla Geranium, Gardenias and other ornamental plants. Mealybugs can also attack bulbs in storage.

When the mealybugs congregate in masses, they cause the plant to look "cottony" in spots. Some of the "cottony" masses may be egg clusters.
Mealybugs are sexually dimorphic: females appear as nymphs, exhibiting reduced morphology, and lack wings, although unlike many female scale insects, they often retain legs and can move. Males are smaller, gnat-like and have wings. Since mealybugs (as well as all other Hemiptera) are hemimetabolous insects, they do not undergo complete metamorphosis in the true sense of the word. However, male mealybugs do exhibit a radical change during their life cycle, changing from wingless, ovoid nymphs to wasp-like flying adults.
Mealybug females feed on plant sap. They attach themselves to the plant and secrete a powdery wax layer (hence the name mealybug) used for protection while they suck the plant juices. The males, on the other hand, are short-lived as they do not feed at all as adults and only live to fertilize the females. Some species of mealybug lay their eggs in the same waxy layer used for protection in quantities of 50–100; other species are born directly from the female.

This group of mealybug killed a prostrate shrub of Pimelea prostrata (New Zealand Daphne).
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Thanks to Wikipedia for some text and information: