About Mealy Bugs

Mealy bugs are insects often found attacking greenhouse and citrus crops. Usually covered with a white cottony substance, the mealy bugs are often clumped together robbing plants of nutrients. Mealy bugs can be found on any part of a plant and can create unsightly damage. Mealy bugs and related insects are most often controlled with insecticides.

Identification

Mealy bugs belong to a group of insects called the scale insects, the superfamily Coccoidea. These insects are generally characterized by wingless females that have a stylet to penetrate and feed on plants, the secretion of a waxy or scale-like body covering and males with no mouth parts. Mealy bugs differ from most other scale insects by having well developed legs and mealy secretions that cover the body and are used to protect newly laid eggs. Mealy bugs range from 1/8-inch to 1/2-inch long and can have a powdery to fuzzy appearance from the waxy secretions. The cottony waxy secretions are the origin of the mealy bug name.

Significance

Mealy bug feeding can cause a plant to lose leaves, grow slowly and even die from feeding stress. Additionally, plant pathogens such as viruses and fungi are often introduced into a host plant. While feeding, mealy bugs will secrete a sugary waste product onto a plant on which dark fungi called sooty mold will often grow. The sooty mold prevents sunlight from reaching the chlorophyll that a plant uses to produce food. Mealy bug damage is most often seen on greenhouse and citrus plants.

Types

Mealy bugs can be found feeding on most parts of a plant depending on the species. Feeding can occur on the ground where the insects feed on the roots or the base of a plant. Other mealy bugs prefer feeding on stems and the point of attachment for a leaf to a stem. Many times the insects can be found clustered and feeding on the underside of leaves. Because the insects suck out plant contents, a plant can lose significant amounts of chlorophyll and carbohydrates.

Prevention/Solution

Mealy bug damage can occur throughout a plant's growing season, so regular monitoring is needed. Mealy bugs are most easily controlled during the crawler stage, which is just after new bugs hatch. This is the period when they are looking for a place to begin feeding, but it lasts no more than one day. Sometimes mealy bugs can be brushed from plants, but after they have anchored themselves, insecticides are often used. Insecticides that move throughout plant tissues are most effective.

Expert Insight

Mealy bugs feed by inserting their stylet into a plant and sucking out the contents. Two holes are located at the tip of the stylet. One hole delivers saliva into the plant to help break down what will be sucked into the other hole. Many mealy bugs lay eggs, but some give birth to living young. After a mealy bug hatches, it inserts its stylet to begin feeding within the first day. Once it begins feeding, it usually remains permanently anchored.