African soft scale

Systematic position and classification. The African soft scale (Coccus africanus) belongs to the order Hemiptera and the family Coccidae. This specialized sap-sucking pest is recognized for its ability to infest various woody plant species, causing economic losses in nurseries and plantations across warm climate regions.

Host plants. This pest exhibits a wide host range, with citrus species, ornamental plants, and coffee trees being particularly susceptible. The insect is often transported via infested nursery stock, making it a significant challenge for quarantine services and commercial plant propagators who deal with international trade.

Biology and life cycle. The life cycle of Coccus africanus involves a transition from mobile crawlers to sedentary adults. Once the crawlers settle on a leaf or twig, they insert their mouthparts into the plant tissue to feed. The females form a protective, waxy covering that makes them resistant to many contact insecticides, complicating control efforts during the adult stage.

Damage and economic impact. Feeding by large populations of soft scales leads to stunted growth, leaf chlorosis, and general tree decline. Furthermore, the excretion of honeydew promotes the growth of sooty mold, which blocks photosynthesis. In severe infestations, the cumulative damage can result in branch dieback and, in extreme cases, the death of the host plant.

Protection measures. Effective management relies on a combination of cultural and chemical strategies. Cultural practices, such as pruning heavily infested parts and ensuring good plant hygiene, are essential. Chemical control is most effective when timed with the crawler emergence stage using systemic insecticides or horticultural oils. Biological control, involving specific parasitoid wasps, is also an important component of integrated pest management (IPM).