Home / Lined Flat Bark Beetles (Laemophloeidae) / Flat Grain Beetle (Cryptolestes pusillus)

Flat Grain Beetle (Cryptolestes pusillus)

The flat grain beetle is a huge pest to grains, mainly wheat, in Canada, though it was initially just a native to Europe. It is commonly found alongside the rice weevil beetle, infesting rice, wheat, and maize. Because of the similarity in color, one could often mistake the reddish-brown flour beetle for the flat grain and vice-versa.

Flat Grain Beetle

Scientific Classification

  • Family: Laemophloeidae
  • Genus: Cryptolestes
  • Scientific name: Cryptolestes pusillus

Physical Description and Identification

Adult

Size: 1.5 to 2.0 mm (0.06-0.078 in)

Color: They have a reddish-brown body.

Other Characteristic Features: As evident from their name, these beetles have a flattened appearance with a ridge-like projection on their head and prothorax, alongside a bead-like antenna.

Cryptolestes pusillus

Larva

They are pale white or yellow, with darkened horn-like abdominal projections and head capsules. Like the adults, the larvae also have a flattened and elongated body, with prominent legs.

Pupa

After 21 days, the larva pupates in a gelatinous cocoon.

Egg

The eggs are white, laid in flour grain or crevices. They take about five days to hatch.

Quick facts

Adult lifespan42 days
DistributionWorldwide, mostly Europe, and Canada from Quebec to British Columbia
HabitatKitchen, cellar, granaries, and in all other places where grains and other food items are stored (especially in high moisture conditions) 
Seasons activeYear-round; but requires heating to survive winter
Diet of larvae and adultsMostly wheat, but even infests rice, maize, and millets; may even feed on bean, copra, cacao, barley, nutmeg, soybean, and cowpea
Flat Grain Beetle Damage

Identifying the Damage Caused by Them

The damage caused by these beetles is not immediately apparent. Still, a heavy infestation may cause grains to get heated and spoiled.

Did you know

  • Swedish entomologist Carl Schonnherr first described its species name in 1817.
  • The adult cannot feed on unbroken grain as they do not have proper mouthparts.
Flat Grain Beetle Picture

Image Source: professionalpestmanager.com, grainscanada.gc.ca, grainscanada.gc.ca, upload.wikimedia.org

The flat grain beetle is a huge pest to grains, mainly wheat, in Canada, though it was initially just a native to Europe. It is commonly found alongside the rice weevil beetle, infesting rice, wheat, and maize. Because of the similarity in color, one could often mistake the reddish-brown flour beetle for the flat grain and vice-versa.

Flat Grain Beetle

Physical Description and Identification

Adult

Size: 1.5 to 2.0 mm (0.06-0.078 in)

Color: They have a reddish-brown body.

Other Characteristic Features: As evident from their name, these beetles have a flattened appearance with a ridge-like projection on their head and prothorax, alongside a bead-like antenna.

Cryptolestes pusillus

Larva

They are pale white or yellow, with darkened horn-like abdominal projections and head capsules. Like the adults, the larvae also have a flattened and elongated body, with prominent legs.

Pupa

After 21 days, the larva pupates in a gelatinous cocoon.

Egg

The eggs are white, laid in flour grain or crevices. They take about five days to hatch.

Quick facts

Adult lifespan42 days
DistributionWorldwide, mostly Europe, and Canada from Quebec to British Columbia
HabitatKitchen, cellar, granaries, and in all other places where grains and other food items are stored (especially in high moisture conditions) 
Seasons activeYear-round; but requires heating to survive winter
Diet of larvae and adultsMostly wheat, but even infests rice, maize, and millets; may even feed on bean, copra, cacao, barley, nutmeg, soybean, and cowpea
Flat Grain Beetle Damage

Identifying the Damage Caused by Them

The damage caused by these beetles is not immediately apparent. Still, a heavy infestation may cause grains to get heated and spoiled.

Did you know

  • Swedish entomologist Carl Schonnherr first described its species name in 1817.
  • The adult cannot feed on unbroken grain as they do not have proper mouthparts.
Flat Grain Beetle Picture

Image Source: professionalpestmanager.com, grainscanada.gc.ca, grainscanada.gc.ca, upload.wikimedia.org

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