MEALYBUGS

Mealybugs are part of the insect families collectively known as scale insects. A diagram of the typical mealybug life cycle is shown in (Photo 1) . Mealybugs are in the Family Pseudococcidae, and are the least scale-like of the group, mainly because they are soft-bodied, without the outer shell associated with insects in the other scale insect families (Diaspididae, the armored scales, and Coccidae, the soft scales). Instead, mealybugs are usually covered with a white waxy powder, and have filamentous projections around the perimeter. Some of these projections can be quite long. At present, there are two main mealybug pest species on greenhouse and interior landscape ornamentals, the citrus mealybug, Planococcus citri, (Photo 2) (Photo 4) and the longtailed mealybug, Pseudococcus longispinus (Photo 3) . Recently, another mealybug species, the hibiscus mealybug (Maconellicoccus hirsutus) has the potential to become a problem on numerous ornamental crops in Florida, and elsewhere. This mealybug, also called the pink mealybug (because when crushed a red fluid comes out) is found now on many of the Caribbean Islands, and may already have invaded Florida. Once an insect establishes itself in a state with a large ornamentals production industry, such as Florida or California, it is only a matter of time before it will spread elsewhere in the U.S. We have no photo of this insect at this time. In contrast with other mealybugs, the body is smooth and waxy, and only has two short projections at the rear of the body. A photo is supposed to be available soon at http://www.ifas.ufl.edu/~apkweb (1996).. Mealybug pests have in common the ability to feed on a very wide range of host plants. They are especially problems on foliage plants in greenhouses and interior plantscapes.

Mealybugs have sucking mouthparts. Feeding weakens and stunts plants, causes leaf distortion, yellowing, and even total leaf loss (Photo 5) . In some cases, plants can be killed. Mealybugs also produce large amounts of honeydew (similar to that produced by whiteflies and aphids), which can coat plants and surrounding surfaces with a sticky layer. A black sooty fungus commonly grows on the honeydew. So, at the very least, mealybugs can make plants look terrible. At worst, plants can be killed. The presence of honeydew and sooty fungus is one way to detect infestations of these insects.

The citrus mealybug female can produce about 600 eggs, which are produced in cottony structures called ovisacs (Photo 2) . Eggs may be produced with or without males. The eggs hatch in less than 10 days into small nymphs called crawlers. The crawlers move about the plants and locate feeding sites. Once the insects settle, there is not much movement. Under favorable conditions, there may be six generations per year. In reality, generations overlap, so all developmental stages will be present.

Longtailed mealybugs (Photo 3) . have a different life cycle. Fewer eggs (about 200) are produced, and females need to mate in order to produce eggs (i.e. males are necessary). Females either produce live young, or the eggs hatch into crawlers very quickly. There are no cottony ovisacs. Longtailed mealybug generation time is longer than the citrus mealybug. As with citrus mealybugs, well-established infestations will have all developmental stages present.

Mealybug Management

There are both chemical and biological control options for mealybug control. The key aspect of management is to detect the infestation before it becomes too difficult and costly to deal with. The chart below includes both chemical and biological controls, and their application rates. Not all of the registered products are listed. Those products that have provided good control in our experiments are included. Also included are those products that growers have reported to be effective. If an infestation is well-established, it will be necessary to make a series of applications, at 10 to 14 day intervals, for mealybug control. Do not use the same pesticide, or pesticide combination, more than three times in sequence.