Ash Weevil

The Ash Weevil (*Myllocerus subfasciatus* and *Myllocerus undecimpustulatus*, family Curculionidae, order Coleoptera) is a destructive, highly polyphagous chewing snout beetle native to Southern Asia that has established invasive populations in tropical and subtropical agricultural regions worldwide. This broad-spectrum pest infests over 150 host plants, with severe economic damage reported in Solanaceous crops (especially brinjal/eggplant, tomatoes, and chilies), okra, cotton, and major fruit orchards (pomegranate, guava, mango, and citrus).

The dual-stage life cycle of the Ash Weevil makes it doubly destructive. Adult weevils are compact (3 to 6 mm long), pearlescent ash-grey to greyish-white beetles with a broad, short snout and faint dark or yellowish-brown maculae on their elytra. Adults feed on above-ground foliage, while their subterranean larvae (grubs)—which are creamy white, legless, C-shaped grubs with light brown head capsules—feed aggressively on root hairs, taproots, and root crowns in the soil.

Diagnosing an Ash Weevil infestation is straightforward due to its signature marginal leaf feeding pattern. Adult beetles chew inwards from the leaf edges, carving out highly distinctive, jagged, semi-circular scalloped notches along the margins. In severe infestations, leaves are skeletonized down to their midribs. Below ground, root grazing by grubs starves the plant of water and nutrients, resulting in generalized chlorosis (yellowing), sudden midday wilting, stunted shoot growth, and complete seedling collapse.

Post-harvest and storage considerations: While primarily a field and orchard pest, adult Ash Weevils frequently hitchhike into produce storage crates, hiding beneath the calyx caps of harvested eggplants, pomegranates, and guavas. In warm, poorly ventilated packing sheds, surviving adults contaminate produce and continue feeding on green calyx tissue, accelerating fungal decay and rendering fruits unmarketable.

Ash Weevils exhibit strong seasonal population spikes during the warm, pre-monsoon and summer months (March to June). A single mated female deposits 300 to 500 tiny, oval, light-yellow eggs in the soil around the root zone. Hatching grubs tunnel through soil for 30 to 50 days before constructing oval earthen pupal chambers. Adult beetles emerge with a lifespan of up to 4 months.

Sustainable Integrated Pest Management (IPM) incorporates cultural, biological, and organic methods. Shaking plant branches in the early morning over a white cloth exploits the weevil's natural thanatosis (playing dead) behavior to collect and destroy adults. Subterranean grubs are effectively controlled using entomopathogenic nematodes (*Heterorhabditis bacteriophora*) and soil-incorporated neem cake. For companion diagnostic guides, consult our Plant Disease Identifier Hub, or view profiles on Root-Knot Nematodes, Cutworms, and Stem Borers.