Mimosa webworm

Taxonomy and origin: The Mimosa webworm (Homadaula anisocentra) is a moth species belonging to the order Lepidoptera, family Galacticidae. Originally native to Southeast Asia, it has become a significant invasive pest in various parts of the world, particularly in North America. It is specifically known for its ability to infest landscape trees, causing both aesthetic and physiological harm.

Host plants and damage: The primary hosts for this pest include the mimosa tree (Albizia julibrissin) and the honeylocust (Gleditsia triacanthos). Larvae feed on the foliage by webbing leaflets together into protective nests. The feeding activity skeletonizes the leaves, eventually turning the foliage brown and causing it to drop prematurely, which significantly impairs the tree's overall vigor.

Life cycle and biology: The Mimosa webworm typically completes two to three generations per year, depending on local climatic conditions. They overwinter as pupae within silk-lined cocoons, often found in bark crevices or surface debris. Adult moths emerge in late spring to mate and lay eggs on the foliage. The larvae hatch and immediately begin constructing their characteristic webbed nests to feed within.

Symptoms of infestation: The presence of Homadaula anisocentra is easily identified by the appearance of unsightly, tangled webbed clusters of leaflets throughout the canopy. As larvae continue to feed, these clusters enlarge, becoming more noticeable. Severe infestations can cover large portions of the tree, leading to complete defoliation by mid-summer in extreme cases.

Control measures: Management of the Mimosa webworm requires a combination of monitoring and timely intervention:

• Manual removal and destruction of small webbed nests during early infestation.
• Application of Bacillus thuringiensis (Bt) sprays targeting young larvae.
• Systemic insecticide applications applied to the soil or trunk to provide long-term protection.
• Encouraging natural predators and parasitoids that help regulate webworm populations in balanced ecosystems.