Citrus flatid planthopper

The citrus flatid planthopper (Metcalfa pruinosa) is a highly polyphagous insect belonging to the order Hemiptera and the family Flatidae. Originally native to North America, it has become a significant invasive pest in many parts of the world, particularly in Europe and the Mediterranean basin, affecting a wide variety of agricultural and ornamental plants.

This pest is known for its extreme versatility, feeding on over 300 plant species. Its favorite hosts include grapevines, various fruit trees like apples, peaches, and citrus, as well as many vegetable crops and ornamental shrubs. Due to its wide host range, the citrus flatid planthopper can easily move between different crops, making management in diverse farming systems quite challenging.

The life cycle of the species consists of a single generation per year. The insect overwinters in the egg stage, with eggs embedded under the bark of host plants. In the spring, nymphs emerge and undergo five developmental stages (instars). During these stages, they produce a distinctive white, woolly waxy secretion that covers their bodies, providing protection against environmental stress and chemical treatments.

The damage caused by Metcalfa pruinosa is twofold. Primarily, nymphs and adults sap the plant’s vital fluids, leading to stunted growth, leaf chlorosis, and wilting. Secondly, the excretion of honeydew promotes the growth of sooty mold, a black fungus that covers leaves and fruit, reducing photosynthesis efficiency and rendering the produce unmarketable due to contamination.

Integrated Pest Management (IPM) is essential for effective control. Cultural practices, such as pruning and destroying heavily infested plant material, are the first line of defense. Chemical control is most effective when targeted at the nymphal stages before they develop full waxy protection. Furthermore, biological control efforts, such as introducing the parasitoid wasp Neodryinus typhlocybae, have shown promising results in long-term suppression of the pest population.