Luna moth

The Luna moth (Actias luna) belongs to the family Saturniidae. While often admired for its striking appearance, in its larval stage, it acts as a defoliator that can impact the health of certain deciduous trees when the population density becomes high enough to cause significant foliage loss.

This pest primarily attacks a variety of host plants, including walnut (Juglans), hickory (Carya), persimmon (Diospyros), sweetgum (Liquidambar), as well as birch, alder, and willow. In nursery settings, infestation of these trees can stunt growth and affect the structural development of young saplings.

The life cycle involves four distinct stages: egg, larva (five instars), pupa, and adult moth. Eggs are deposited on the underside of leaves. Once hatched, the larvae feed continuously for several weeks. When development is complete, they construct a silken cocoon, often within a shelter of leaf litter on the ground to overwinter.

The damage is characterized by extensive leaf consumption. Young larvae perform skeletonization, while mature larvae consume entire leaf blades, leaving only the midribs. Repeated or severe defoliation weakens the tree's vigor, making it more susceptible to environmental stress, secondary pests, and various plant diseases.

Management strategies include:

• Manual removal of caterpillars from small trees or susceptible shrubs.
• Sanitation by removing leaf litter where cocoons pupate during the autumn/winter.
• Encouraging natural predators such as birds, parasitic wasps, and tachinid flies.
• Using biological insecticides, such as BT, only as a last resort when threshold levels of defoliation are exceeded.