Mealybugs

Mealybugs (or mealy bugs) are tiny insects found on plant stems and leaves (see also root mealybugs). In spring, newly hatched mealybugs known as 'crawlers' move onto young shoots where they settle on the underside of leaves. These areas can be difficult to spray, but effective coverage is the key to mealybug control.

Mealybugs are covered with a pale 'mealy' thread-like or powder-like protective coating. The bugs feed by sucking on the plant sap. Mealybugs excrete a sticky substance called honeydew which ants and wasps like to feed on. Ants may farm mealy bugs by protecting them from attack so that they can feed on the honeydew.

The honeydew also provides a perfect medium for sooty mould growth. Often leaves of infested plants have sticky white patches of bugs and/or black sooty mould.

Mild temperatures and high humidity are perfect conditions for mealybugs to breed but prolonged hot weather reduces numbers. Damaging infestations can occur on citrus trees, daphne, and other ornamental plants. Orchids and ferns, especially in greenhouse, can also become infested. Mealybugs will attack bulbs in storage and the roots of some plants.