Rice Weevil

The rice weevil is a small snout beetle in the family Curculionidae, one of the most economically significant insects associated with stored grain worldwide. Despite its name, it feeds on a wide variety of cereal grains and grain products, not just rice, making it a broadly distributed pest of stored agricultural commodities.

Like other true weevils, it possesses an elongated, downward-curving rostrum, or snout, tipped with small chewing mouthparts, which it uses to bore into individual grain kernels. This body plan is characteristic of the enormous weevil family, one of the most species-rich groups of beetles on Earth.

The rice weevil is capable of flight, unlike its close relative the granary weevil, and can disperse to infest new grain stores, which has contributed to its worldwide distribution alongside the movement of stored grain through trade.

• Adult: 2–3 mm, small and reddish-brown to nearly black, with a long, slender, curved snout typical of true weevils.
• Elytra bear four faint, pale reddish or yellowish spots arranged in a rough square pattern, though these can be subtle.
• Fully developed hind wings beneath the elytra allow it to fly, unlike the closely related granary weevil.
• Lookalikes: nearly identical to the granary weevil in size and shape, but the rice weevil has the pale spotting on its elytra and can fly, while the granary weevil is uniformly dark and flightless.

Found worldwide, particularly in warmer climates, wherever grain is stored, including granaries, warehouses, mills, shipping containers, and household pantries. It infests whole grain kernels of rice, wheat, corn, and other cereals, and can be active year-round in heated indoor storage conditions.

Adults feed on grain kernels and use their snout to chew entry holes for egg-laying, while larvae develop and feed entirely within a single grain kernel, hollowing it out from within. Because it retains functional wings, the rice weevil can fly between grain sources, contributing to the spread of infestations. As a stored-product pest, it is of considerable interest in agricultural and food storage contexts due to the scale of grain it can affect.

Females chew a small pit into a grain kernel, deposit a single egg inside, and seal the hole with a gelatinous secretion. The larva develops entirely within the kernel, feeding on the starchy interior, then pupates inside the same hollowed-out grain. Adults chew their way out of the kernel upon completing development. In warm conditions, the rice weevil can complete multiple overlapping generations per year, with development from egg to adult taking roughly one month.