Description of the Pest
Nymphs and adult female mealybugs (order Pseudococcidae) are soft, oval, white powder- or wax-covered insects. Adult males are tiny, two-winged insects with two long tail filaments, but are rarely seen. In many mealybug species the female lays tiny yellow eggs in an ovisac, a mass of eggs intermixed with white wax. Longtailed mealybug produces no external egg sacs; it gives live birth to nymphs. Longtailed mealybug has two to four overlapping generations a year. All stages can occur throughout the year.
Longtailed mealybug is the only species common in California avocado. Other species to look out for because they can potentially infest avocado include citrus mealybug (Planococcus citri), pink hibiscus mealybug (Maconellicoccus hirsutus), and vine mealybug (Planococcus ficus), none of which are reported pests of avocado in California.
The citrus, longtailed, and vine mealybugs have distinct, well-developed wax filaments around their body margin. Female longtailed mealybugs have tail filaments almost as long as the body length. Citrus and vine mealybug filaments are relatively short. Pink hibiscus mealybug lacks distinct waxy filaments.
Correct identification of mealybugs is important to control. Ask an expert for help if you encounter an unfamiliar mealybug species. For example, the introduced vine mealybug has not been found in California groves, but it infests avocado elsewhere in the world. Pink hibiscus mealybug in California has been limited to Imperial and Eastern Riverside Counties, an area with few avocado groves. Introduced parasites, especially Anagyrus kamali (Encyrtidae), are providing good biological control of pink hibiscus mealybug. If pink hibiscus mealybug is discovered in California outside of Imperial and Eastern Riverside Counties, notify agricultural officials as prompt management action may be warranted.
Mealybugs suck phloem sap. When common, they can reduce tree vigor, foul plants with sticky honeydew, and promote growth of blackish sooty mold that fouls fruit. Mealybug numbers are usually very low in avocado. They occasionally are pests of young trees. New scion grafts on old (top-worked) trees have sometimes been damaged by longtailed mealybugs, which can become common during late winter to early spring.
Pesticide application is not recommended for mealybugs in avocado. Conserve natural enemies that control most mealybug populations.
- Selectively controlling sugar-feeding ants causes longtailed mealybug numbers to decline and can prevent outbreaks. Ants protect mealybugs from natural enemies (honeydew is an ant food source) so eliminating ants allows natural enemies to attack.
- Reduce dust, which also interferes with natural enemies.
- Whenever possible, apply only selective or short-residual pesticides when treating other pests.
Mealybug predators include green lacewing (Chrysoperla spp.) larvae, pirate bugs, predaceous fly larvae, and lady beetles, such as the mealybug destroyer (Cryptolaemus montrouzieri). Parasitic wasps are especially important in controlling outbreaks because the wasps specialize on mealybugs and reproduce rapidly. Acerophagus notativentris, Arhopoideus peregrinus, and Anarhopus sydneyensis (family Encyrtidae) parasitize longtailed mealybug.
Organically Acceptable Methods
Use biological control on an organically certified crop.