Larger grain borer

Classification

Primary pest; Grain feeder
Order: Coleoptera
Family: Bostrichidae
Acronym: PTR

Description

• 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.

Similar species

• Lesser grain borer (Rhyzopertha dominica)
• Ghoon beetles (Dinoderus species) – not found in Canada

Commodities affected

• 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

• 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

• Control grain insect pests

Geographic range

• Is distributed throughout tropics but not established in Canada

Where found

• 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

Life history

• 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.