Pseudococcidae

Mealybugs are distinguished from other scale insects by their soft, unarmored bodies covered in white, powdery wax secretions. Unlike armored scales (Diaspididae), they lack a hard protective covering. Adult females are typically oval-shaped, 2-5 mm in length, and often possess waxy filaments or projections around the body margin. Males are smaller, winged, and short-lived. Species-level identification requires slide-mounting of adult females and examination of morphological characters such as the number and arrangement of circuli, presence of oral rim ducts, and other microscopic features. A new field diagnostic using 10% potassium hydroxide or 5% sodium hydroxide causes hemolymph of Nipaecoccus viridis to turn green—a unique reaction among tested species.

Mealybugs inhabit moist, warm climates and are found in diverse environments including greenhouses, interiorscapes, agricultural crops, subtropical forests, and urban landscapes. They occur on all plant parts including leaves, stems, fruits, flowers, and roots. Many species thrive in protected environments such as under sepals, in leaf axils, and beneath bark crevices. Invasive species have established in Mediterranean regions, Florida, California, and other subtropical to tropical areas worldwide.

Pseudococcidae has a cosmopolitan distribution with highest diversity in tropical and subtropical regions. Approximately 320 species occur in the United States, with 70-80 species documented in Florida alone. Notable invasive distributions include: Nipaecoccus viridis in Florida (since 2009), the Caribbean, and recently intercepted in Maryland, North Carolina, and Texas; Phenacoccus peruvianus throughout the Mediterranean Basin (first reported Spain 1999); Maconellicoccus hirsutus across multiple continents; and Planococcus ficus in grape-growing regions worldwide. GBIF records document presence in Denmark, Norway, and Sweden.

In warm climates, mealybugs complete multiple overlapping generations annually with year-round activity. In temperate regions, outdoor populations decline or perish during winter cold, surviving only in protected microhabitats or greenhouses. Seasonal population dynamics vary by species: Phenacoccus peruvianus shows peak populations in spring and summer, declining to nearly undetectable levels in autumn and winter. Citrus mealybug (Planococcus citri) completes several generations annually in Florida and California but cannot survive winter outdoors in most US states.

All mealybugs are phytophagous, feeding exclusively on plant phloem sap by inserting piercing-sucking mouthparts. They are highly polyphagous, with many species recorded from dozens to hundreds of host plant species across multiple families. Specific examples include: Nipaecoccus viridis on citrus, hibiscus, oleander, jatropha, blueberry, and hemp; Phenacoccus peruvianus on Bougainvillea glabra and numerous ornamental plants; citrus mealybug on citrus, grapefruit, banana, and plants from over 60 families. Feeding causes direct damage through nutrient removal and indirect damage via honeydew excretion and sooty mold development.

Mealybugs exhibit incomplete metamorphosis with three life stages: egg, nymph, and adult. First-instar nymphs (crawlers) are the dispersal stage, moving via walking or wind currents to locate new hosts. Females progress through three instars before reaching adulthood; males develop through two nymphal instars followed by a prepupal and pupal stage within a cocoon, emerging as winged adults. Females are typically flightless and sessile as adults. Reproduction is often parthenogenetic (thelytoky) in many species, with females producing 300-600 eggs without mating. Some species reproduce sexually or exhibit both modes. Development rates vary with temperature; parasitoid development in associated species occurs in 20-22 days at 25°C.

Mealybugs exhibit cryptic feeding behavior, often concealing themselves under sepals, in bark crevices, or leaf axils where they are difficult to detect. They excrete copious honeydew, establishing mutualistic relationships with ants that tend them for this sugar source and provide protection from predators. When disturbed, many species exhibit reflex bleeding from dorsal ostioles—slit-like openings that release waxy, defensive fluid that can gum up predator mouthparts. First-instar crawlers may engage in phoresy, attaching to mobile insects or wind currents for dispersal. Some species show aggregated spatial distributions on preferred plant tissues.

As primary consumers, mealybugs convert plant phloem into biomass available to higher trophic levels. They serve as hosts for diverse parasitoid wasps (Encyrtidae, Aphelinidae, Signiphoridae) and prey for predators including lady beetles (Coccinellidae), lacewings (Chrysopidae), minute pirate bugs (Anthocoridae), and syrphid flies. Their honeydew supports sooty mold fungi and attracts ants, altering community dynamics. Invasive mealybugs disrupt native ecosystems and agricultural systems, competing with native herbivores and necessitating biological control introductions. The mealybug destroyer (Cryptolaemus montrouzieri), a lady beetle native to Australia, has been introduced globally for classical biological control.

Mealybugs are economically significant pests of agriculture, horticulture, and forestry worldwide. They damage citrus, grapes, coffee, cacao, cotton, ornamentals, and greenhouse crops through direct feeding and honeydew/sooty mold contamination. The family includes numerous regulated invasive species subject to quarantine and eradication efforts, including Nipaecoccus viridis, Maconellicoccus hirsutus, and Phenacoccus peruvianus. Management relies on integrated pest management combining biological control agents (parasitoids and predators), selective insecticides, and cultural practices. Thirteen mealybug species have invaded Florida since 1998, with 82% of Florida's mealybug fauna being non-native. Accurate species identification is critical for regulatory decisions and effective management.

• Diaspididae (armored scales)Armored scales possess a hard, separable protective covering (test) formed from exuviae and wax, unlike the soft, unarmored bodies of mealybugs. Diaspididae lack the powdery wax coating and typically appear as flattened, immobile disks on plants.
• Coccidae (soft scales)Soft scales also produce waxy coverings but typically lack the filamentous, mealy appearance of Pseudococcidae. Adult female Coccidae are often larger, more convex, and produce less conspicuous waxy secretions; they also differ in internal anatomy and life history traits.
• Monophlebidae (giant scales)Giant scales are larger, often with prominent waxy processes, but differ in body structure and are less commonly encountered as pests. They typically have more restricted host ranges and different geographic distributions.

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Publications | Entomology Research Museum
• From the mailbag – Mealybugs, Pseudococcidae, in the greenhouse and their destroyer, Cryptolaemus montrouzieri — Bug of the Week
• Trash Bug Versus Mealybug: Unique Insect Interaction Filmed for First Time
• Here We Go Again: Another Invasive Pest in Florida Citrus
• Green Light: New ID Test Ready for Invasive Mealybug Pest
• Archive — Bug of the Week
• A Mealybug Phenacoccus multicerarii Granara de Willink (Hemiptera: Pseudococcidae)
• Biology and management of the invasive mealybug Phenacoccus peruvianus (Hemiptera: Pseudococcidae) in urban landscapes