Canadian Grain Commission
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European grain moth
Nemapogon granella (Linnaeus)
Order: Lepidoptera
Family: Tineidae
Acronym: NGR
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Ecology
The European grain moth is found in North America, Argentina, Europe, Northern Asia and Australia. It is more common in temperate regions. The moth is found in granaries, mills, warehouses, elevators and wine cellars. It is moderately cold hardy. It feeds mostly on cereals that have a high moisture content. The moth feeds on rye, wheat, barley, oats, corn, soybeans, rice, nuts, seeds, dried fruit and mushrooms. It is also reported to infest wine corks.
Damage
The European grain moth infests cereal grains that have a moisture content higher than 14%. The larva feeds first on the germ, then on the endosperm of a kernel. Damage is not distinct and is caused by larval feeding. In a grain bulk, the larva infests the top 5 – 6 cm of the grain. The larva produces silk webbing when it feeds. This webbing binds the surface of the grain bulk together. Signs of infestation are a disagreeable odor, clumped grain and contamination with silk and frass.
Life history
The adult European grain moth has a wing span of 9 - 14 mm. The head is covered in spiky hairs. The forewing is white with a basal black bar and mottled with dark bronze-brown patches and spotted with black. The hind wings are brown or grey and are fringed with long hairs. The hind wing is narrower than the forewing. The adult does not feed on the commodity. The adult can fly. It is short-lived. Its lifespan is 7 – 21 days.
The female lays between 30 – 220 eggs. On average, the female lays 100 eggs. The female lays eggs singly in a food source or in dust, debris or on bags.
The larva is white. It grows to be 7 - 10 mm long. It is active. The larva’s head ranges in colour from pale yellow to reddish brown to dark brown. The thoracic plates are yellowish to pale brown. The optimal conditions for development are a temperature of 25°C and relative humidity of 90%. The time required for development is 70 days. In Canada, 2 generations of European grain moth can develop per year. When the larva is mature, it actively leaves the food source and searches for a site in which to pupate. The larva pupates in a silk cocoon. The mature lave of the second generation overwinters and pupates in the spring.
