Cottony citrus scale

Taxonomic position: The cottony citrus scale (Pulvinaria citricola) belongs to the order Hemiptera and the family Coccidae (soft scales). It is recognized as a significant pest of citrus crops, causing economic losses in subtropical regions worldwide.

Host plants: This pest primarily infests various citrus species, including lemons, oranges, and mandarins. Occasionally, it can also be found on a variety of ornamental plants, such as Pittosporum and bay laurel, often serving as a reservoir for the infestation of neighboring citrus orchards.

Biology and life cycle: The life cycle consists of the egg, nymph (crawler), and adult stages. Adult females are distinguished by the production of a conspicuous white, cottony egg sac containing hundreds of eggs. Reproduction is primarily parthenogenetic. The dispersal phase occurs during the crawler stage, as these nymphs are mobile and can crawl between leaves or be transported by wind or human activities.

Nature of damage: By feeding on phloem sap, the scale insects weaken the host plant, leading to yellowing of leaves, stunted growth, and premature fruit drop. A major consequence of their infestation is the secretion of honeydew, which promotes the growth of sooty mold. This fungus blackens the foliage and fruit, interfering with photosynthesis and reducing the overall market quality of the harvest.

Control measures: Integrated Pest Management (IPM) is essential for effective control. Cultural practices, such as pruning heavily infested branches, help reduce population density. Chemical control should be timed with the peak emergence of crawlers, utilizing systemic insecticides or narrow-range horticultural oils. Encouraging natural enemies, such as parasitoid wasps and lady beetles (Coccinellidae), is also highly recommended to provide long-term biological suppression of the pest.