Mealybug

Mealybugs are soft-bodied, sap-sucking insects related to scale insects. Adult females are wingless, oval and flattened, typically 2–5 mm long, covered in a white to grey mealy or waxy secretion that gives them a cottony appearance. Many species have short waxy filaments radiating from the body edge, and some, such as the long-tailed mealybug, have distinctly elongated tail filaments. Adult males are rarely seen; they are small, gnat-like and winged, living only briefly to mate. Nymphs (crawlers) are the mobile immature stage, pale yellow to pinkish and initially lacking wax, becoming increasingly waxy-coated as they mature and settle to feed. Mealybugs cluster in protected sites such as leaf axils, along stems, under bark, in flower and fruit clusters, and on roots and crowns below the soil line, where root-feeding species can be mistaken for soil mealybugs or root aphids.

Mealybugs belong to the family Pseudococcidae and comprise many species affecting ornamentals, nursery stock, turf, fruit and vegetable crops across Australia. Common pest species include citrus mealybug, longtailed mealybug, hibiscus mealybug, and grass or couch-crown mealybugs affecting turf.

They are found throughout Australia, with populations building over the warmer months and persisting year-round in protected environments such as glasshouses, shadehouses and nursery production areas. Outdoors, numbers typically peak in spring and autumn in temperate regions and can remain active year-round in warmer climates. Ants are frequently associated with infestations, as they farm mealybugs for their honeydew and protect them from natural enemies.

Management relies on regular monitoring of new stock and susceptible plants, particularly in nursery production where mealybugs spread readily on cuttings, pots and dense foliage. Cultural controls include improving airflow, avoiding excess nitrogen which promotes soft new growth, controlling ants, and physically removing light infestations. Biological control by parasitic wasps and predatory beetles (such as mealybug ladybirds) can be significant where broad-spectrum insecticide use is minimised. Chemical control is most effective against the mobile crawler stage, as later stages are protected by their waxy coating.