Lesser grain borer

Rhyzopertha dominica (F.)


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


  • Adults are dark reddish brown and 3 mm long with distinctly shaped, loose 3-segmented club.
  • Larvae are white and c-shaped. They are immobile at maturity with dark head capsule.


Similar species

Commodities affected

  • Nearly all grains, especially wheat, barley, sorghum and rice
  • Seeds, dried fruit, drugs, cork, wood and paper products

Signs of infestation

  • Large amounts of flour
  • Tunnels and irregularly shaped holes in commodity
  • Sweet odour in the grain


  • Damage is distinctive and heavy
  • Adults and larvae feed on germ and endosperm reducing kernels to shells of bran
  • Adults and larvae also burrow through kernels

How to control

Geographic range

  • Is found worldwide and across Canada, although is not common in all provinces
  • Is not well established in Canada due to colder climate

Where found

  • Is most common in buildings; may be found in shipping containers

Life history

  • Lesser grain borer is one of the most injurious pests known to attack grain.
  • Adults are mobile, able to fly and are long-lived.
  • Females lay eggs one at a time or in batches of up to 30 eggs.
  • Larvae live within the seed and are rarely found in sieve samples.
  • Larvae pupate within grain kernel.


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