Maize weevil

Classification

Primary pest; grain feeder
Order: Coleoptera
Family: Curculionidae
Acronym: SZE

Description

• Adults are identical in external appearance to the rice weevil (Sitophilus oryzae); dissection required to distinguish between the species.
• Adults are reddish brown beetles with a characteristic long weevil snout and have 4 yellow to red spots on the elytra.

Similar species

• Granary weevil (Sitophilus granarius),
• Rice weevil (Sitophilus oryzae) – morphologically nearly identical

Commodities affected

• Grain, pasta

Signs of infestation

• Damaged kernels with ragged holes
• Increased heat and humidity in pockets of grain

Damage

• Damaged kernels with ragged holes
• Larvae feed internally and newly emerged adults leave a ragged exit hole and will also feed on the damaged kernel.
• Maize weevil infestations produce heat and moisture.

How to control

• Control grain insect pests

Geographic range

• Is abundantly distributed in tropical environments throughout the world, where it is able to infest standing crops
• Is less common in temperate zones and, in Canada, has only been found in Ontario and Quebec

Where found

• Is found in granaries, stores, elevators
• Tends to aggregate within grain bulks, making populations difficult to detect

Life history

• Adults can fly.
• Adult beetles are long-lived (3 to 6 months or more).
• Adult females lay eggs singly by first chewing a small hole in the grain, then depositing the egg into the hole then sealing with a mucus plug
• Larvae hatch and feed internally within the kernel.