Lesser grain borer (Rhyzopertha dominica)

Lesser grain borer

Invasive. The origin of the lesser grain borer is unknown.

Found across Australia and worldwide


Larvae are a white and up to 3.0mm long. They are “straight” and mobile when young, but become more C-shaped and less mobile as they age.


The lesser grain borer is a cylindrical, reddish beetle, 2.5-3.0 mm long. The head is usually held downward, concealed under the thorax. The antennae is club-shaped with 3 segments.


Female beetles lay between 200-500 eggs during her life-time.

The life-cycle is completed in around 8 weeks. Larvae go through 4  instar stages before pupating.

Adults live for 2-3 months.

Lesser grain borers primarily target grain, but will also feed on processed grains – cereals, biscuits and spaghetti.

Both the adult and larvae feed and cause damage.

Lesser grain borers are the biggest pest of stored grain in Australia.


The lesser grain borer is a strong flyer.

Females lay their eggs loosely among the grains and the larvae borer into the grain.

Infested grain will give off a sweet smell.

  • Check all incoming food materials
  • Place all opened food stuffs in sealed plastic containers
  • Clear up any food spills

Monitoring and treatment notes:

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