Royal moth (Biston regalis)

The Royal moth (Biston regalis) belongs to the Geometridae family within the order Lepidoptera. It is recognized as a significant foliage-feeding insect that targets various deciduous trees, posing a potential risk to orchards, forestry, and ornamental gardening in its native habitats.

This pest primarily feeds on the leaves of a wide range of host plants. The larvae, commonly known as inchworms, show a high preference for succulent young foliage. During heavy infestations, the larvae can consume large amounts of leaf tissue, leading to substantial canopy reduction and tree stress, which negatively impacts the plant's overall health and vigor.

The biology of Biston regalis is characterized by a complete metamorphosis involving four distinct stages: egg, larva, pupa, and adult. The insect typically undergoes winter diapause in the pupal stage, usually buried within the top layers of the soil or leaf litter. Adult emergence coincides with the warming of spring, followed by mating and egg-laying on host plant surfaces.

Damage assessment reveals that the primary harm is caused during the larval stage. When populations peak, the feeding activity can lead to rapid defoliation of trees, causing significant economic damage in commercial orchards. Young plants are particularly vulnerable, as repeated defoliation events can prevent normal development and sometimes lead to tree death.

Integrated pest management (IPM) strategies for controlling Biston regalis include:

• Cultural control: Soil cultivation in late autumn and early spring to expose and destroy pupae.
• Biological control: Encouraging natural predators and using bacterial insecticides like Bacillus thuringiensis.
• Chemical control: Targeted application of environmentally safe insecticides during the early larval instar stages.
• Monitoring: Using pheromone or light traps to detect adult flight patterns and time interventions accurately.