Orange-striped oakworm

The Orange-striped oakworm (Anisota senatoria) is a moth species belonging to the family Saturniidae. It is well-known as a significant defoliator of oak trees in North American forests and landscapes, often causing concern when population levels spike and lead to extensive foliage loss on mature trees.

The primary host plants for this pest include various species of oak, particularly those in the white oak group. While oaks are the preferred food source, under severe infestation conditions, the larvae may also feed on other woody plants like hazel or chestnut, causing widespread damage within a localized area.

The life cycle of the insect consists of a single generation per year. Adult moths emerge in early summer, and females lay clusters of eggs on the underside of leaves. Upon hatching, the larvae exhibit gregarious behavior, feeding in groups, which makes them highly visible as they skeletonize the foliage during their early stages of development.

Damage is characterized by the consumption of leaf tissue, leaving only the veins or causing total defoliation of the canopy. As the larvae mature, they develop the iconic orange or yellow longitudinal stripes and two prominent horns on the second thoracic segment, which serve as key identification markers for arborists and foresters.

Management strategies focus on integrated pest management (IPM) practices. For small trees, physical removal and disposal of egg clusters or young larvae are highly effective. For larger areas or severe infestations, applications of Bacillus thuringiensis (Bt) are recommended, as they selectively target caterpillar stages with minimal impact on beneficial insect populations.