Grain Weevil
Scientific name: Sitophilus granarius
Other common name: Grannay weevil
Family: Curculionidae
Distribution
Distributed throughout temperate regions, rare in tropical countries.
Pest Type
Primary pest
Identification
Adults are 3.0–5.0 mm in length with elongated snouts. They are dark brown, oval, and have long legs. The thorax has oval-shaped punctures. Their elytra do not have any patterns; they do not have any flight wings under the elytra, therefore they cannot fly. The larvae are apodous or they do not have any legs and the head is reduced. This species is very similar to S. oryzae and S. zeamais.
Life Cycle
At optimum conditions of 30℃ temperature and 70% relative humidity, the life cycle will be completed in 25 days. The females lay eggs singly inside a grain, then covers it with a waxy plug. The larvae hatch inside the grain feeding on its inside, remaining concealed until they hatch from the pupae and emerge as adults. On emergence, the adults leave ragged holes in grains, reducing the quality and market value.
Commodities attacked
Cereal grains
Economic Importance
High, infestations can cause the grain to heat and develop moulds.
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