Cottony scale

The genus Pulvinaria belongs to the Coccidae family, commonly known as soft scales. These insects are distinguished by the white, cotton-like ovisac produced by the female during the egg-laying phase. This distinct feature makes them easily recognizable on the stems and leaves of various infested host plants.

These pests have a broad host range, damaging various agricultural and ornamental plants. They are frequently found on citrus trees, peach trees, grapes, and many landscape shrubs. In greenhouses, Pulvinaria species can cause severe outbreaks, especially in environments where natural predators are absent.

The biology of this pest involves an egg stage protected within the ovisac, followed by a mobile crawler stage. The crawlers are the primary dispersal mechanism, moving to new feeding sites before settling down to develop into sedentary adults. Some species may complete multiple generations per year depending on the regional climate.

Damage is caused by the insects feeding on plant phloem sap, which deprives the plant of essential nutrients. Furthermore, the excretion of honeydew promotes the growth of sooty mold, which covers the foliage. This layer prevents light penetration and impairs photosynthesis, often resulting in yellowing leaves, stunted growth, and reduced fruit quality.

Effective management strategies include:

• Regular scouting to identify the crawler stage for timely insecticide application.
• Application of systemic insecticides to target sedentary stages.
• Use of horticultural oils to suffocate eggs and nymphs.
• Encouragement of natural enemies such as parasitoid wasps and predatory beetles.
• Pruning and destruction of heavily infested branches to reduce local population pressure.