Sitophilus zeamais Motschulsky
Primary pest; grain feeder
- 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.
- Grain, pasta
Signs of infestation
- Damaged kernels with ragged holes
- Increased heat and humidity in pockets of grain
- Damage is distinctive; both adults and larvae feed directly on the kernel.
- 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
- 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
- Is found in granaries, stores, elevators
- Tends to aggregate within grain bulks, making populations difficult to detect
- Adults can fly.
- Aadult 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.
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