If something is described as "mealy", it usually means that it is soft and mushy...well, that describes mealybugs. They are soft-bodied relatives of scale insects that get their name from the white or gray threads of waxy material that covers their bodies. In heavy infestations, the plant may look as if it is covered with cotton.

Mealybugs are sucking insects that make their living draining the sap from plants similar to aphids, scale and spider mites. Their feeding can result in leaf distortion, yellowing due to loss of chlorophyll, stunting, formation of galls and, in extremes, the death of twigs, stems or the whole plant.

The larvae, called crawlers, move around a plant looking for a place where they may feed. Unlike scale, the mature females can move around a little on the plant. Adult males develop wings and look like tiny flies. They do not feed and die after mating with the female.

As with most sucking insects, one of the signs of infestation is the development of a black coating called sooty mold on the leaves or stems of the plant. This fungus is growing on the sticky discharge called honeydew that come from sucking insects.

First, as always, you must properly identify the species of the mealybug on your plants. Consult your local Extension Service office or other plant professional. They should be able to tell you the life cycle of that species and when the young (crawlers) are active.

Three approaches may be taken to reduce the number of mealybug on the plant:

1. A dormant (horticultural) oil spray may be used to smother both the adults and the crawlers. Plants may be sprayed with a highly refined petroleum product such as Volck oil or Sunspray Ultra Fine oil at the dormant rate. The temperature must be high enough (usually 40 degrees for several days) so that the oil will spread evenly over the branches and thus smother the mealybugs.

 2. When the crawlers emerge, they may be controlled by an oil spray applied at the growing season rate (more dilute) listed on the product. Or, they may also be treated with other insecticides labeled for your species of mealybug. 

3. Some systemic insecticides may be labeled for use on scale. Check the label of the product to be sure that the species of mealybug and your species of plant(s) are listed.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

Types of Insects

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