Indian Meal Moth (Plodia interpunctella)
Adult moths are about 8 to10mm long when at rest and have a wing spread of about 18 to 20mm. When viewed from above with the wings folded over the back, the outer 1/3 of the wing appears reddish-brown or bronze coloured “at the wing tips” while the inner 2/3 of the wing “at the basal portion” is light grey to ochre-yellow. Also, the head and thorax are reddish-brown and the hind wings grey. Brown-headed larvae are dirty white, sometimes tinged pink or green.
The female moth lays between 60 and 300 eggs, singly or in clusters, on or near the foodstuffs. Eggs hatch in 2 to 14 days with larvae or “tiny whitish caterpillars” dispersing within a few hours. Larvae move to foodstuffs, and feed in or near a tunnel-like case of frass and silk which they web together. Under good conditions, the entire life cycle requires six to eight weeks and can be active all year round. However, in cold climates, larvae over-winter and pupate in March.
Controlling this pest requires careful inspection of all stored cereal foods, discarding the heavily infested material. Flour dust and other debris in cracks and crevices needs to be cleaned away or vacuumed. Following cleaning, treatment can be carried out using a residual insecticide, or ULV for larger infestations or big areas.