Larger grain borer
Prostephanus truncatus (Horn)
Primary pest; Grain feeder
- Adults are black or brown and cylindrical in shape, heads face down.
- Adults are slightly larger (3 to 4 mm) than the lesser grain borer.
- Posterior end of the elytra slope back with two strong lateral ridges with sharp edged corners.
- Larvae are grub-like with poorly formed legs and are less mobile as they mature.
- Lesser grain borer (Rhyzopertha dominica)
- Ghoon beetles (Dinoderus species) – not found in Canada
- Primarily affects maize
- Also affects dried root crops, bamboo, rattan, cassava, wheat, sorghum, dried sweet potato
- Will bore into, but does not feed on, cowpea, cocoa, haricot, coffee, rice
Signs of infestation
- Characteristic damage is extensive tunneling.
- Readily visible holes are bored in seeds.
- Copious amounts of flour are produced.
- Damage is distinctive and heavy.
- Adults burrow extensively leaving tunnels and irregular shaped holes.
- Feeding produces large quantities of flour.
- Larval feeding and burrowing contributes further to adult damage.
How to control
- Is distributed throughout tropics but not established in Canada
- Is very tolerant of hot conditions and dry grain
- Can establish where maize (corn) is stored on the cob and infestation can occur prior to harvest
- Females lay eggs singly or in batches in or near food.
- Newly hatched larvae bore into grains or feed on damaged grain and flour produced by adult feeding.
- Larvae can successfully develop within a single seed.
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