Scalloped Hazel

The Scalloped Hazel (Ligdia adustata) is a moth species belonging to the family Geometridae within the order Lepidoptera. Despite its common English name, this moth is primarily recognized in agricultural and horticultural contexts as a specialized pest of the genus Euonymus (spindle trees).

The host plants are primarily various species of spindle (Euonymus), which are widely cultivated for their ornamental value. The larvae feed on the foliage, and while they do not typically cause tree mortality, their defoliation can significantly weaken host plants, especially in nursery settings or urban landscaping where aesthetic appearance is vital.

The life cycle of the Scalloped Hazel involves complete metamorphosis, typically consisting of two generations per year in temperate climates. The insect overwinters as a pupa, usually protected within a cocoon in the leaf litter or just below the soil surface. Adults emerge in spring, with the activity of the second generation occurring later in the summer.

Damage is characterized by the feeding activity of the larvae, which can result in skeletonized leaves or complete defoliation. High larval densities during outbreaks cause significant aesthetic damage. Furthermore, the loss of leaf surface area interferes with the plant's ability to photosynthesize, which can stunt growth and impact the overall health of the shrub.

Effective management strategies for this pest include:

• Sanitation practices such as clearing leaf litter to remove overwintering pupae.
• Cultivating the soil beneath infested shrubs to disrupt the pupal stage.
• Using biological control agents like Bacillus thuringiensis during the early larval instars.
• Application of selective insecticides if heavy infestation levels threaten plant survival.
• Monitoring adult flight activity to time potential interventions correctly.