Scientific Name: Tribolium castaneum (Herbst, 1797)
Common Names: Red flour beetle, bran bug, rust red flour beetle, flour beetle, rust red flour beetle
Synonyms
Colydium castaneum
Taxonomic Position
Phylum: Arthropoda
Class: Hexapoda (Insecta)
Order: Coleoptera
Family: Tenebrionidae
Host Range
The red flour beetle has a very broad host range. It is a major pest of the following crops among others: maize, groundnut, oats, Brazil nut, barley, walnuts, lentil, rice, beans, peas, almond, rye, sorghum and wheat. The red flour beetle also attacks a wide range of dried stored products.
Pest Destructive Stage
Secondary Pest
Adult and larva which feed mainly on the germ of the cereal.
Damage Symptoms
Seeds and grains: internal feeding; contamination with faeces, promoting mould. Infestation can lead to persistent disagreeable odours in the commodity due to secretion of benzoquinones from abdominal glands.
Identification features
Eggs
- Eggs are approximately 0.5 mm long, cylindrical and white or colourless. They are sticky which causes them to become covered in flour and stick to containers.
Larva
- The larvae are elateriform, yellowish-white, slender, and cylindrical and covered with fine hairs.
- The head is pale-brown and the last segment of the abdomen has two upturned dark, pointed structures.
Pupa
- The pupa does not have a cocoon and is yellowish-white, becoming brown later.
Adult
- The adult red flower beetle is approximately 3-4 mm long with a flattish curved-sided body which is reddish-brown in colour.
- The head and upper part of the thorax are covered with minute punctures and the wing cases (elytra) are ridged along their length.
- The antennae are enlarged at the tip (capitate) with the last three segments wider than preceding segments.
- The eyes are reddish-black in colour.
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T. castaneum – Dorsal View, Antenna, Head front showing antennae and eye
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T. confusum – Dorsal View, Antenna, Head front
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Similar Species
It is possible to confuse the red flour beetle (Tribolium castaneum) with the ‘confused flour beetle’ (Tribolium confusum).
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Distinguishing Characters
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Tribolium casteneum
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Tribolium confusum
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Eyes
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Eyes of the red flour beetle are larger and closer together and eyes divided by a projection of the head with narrowest portion is at least 3-4 facets wide
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width of the eyes of T. confusum is about a third of the space separating them and Eyes deeply divided by a projection of the head with narrowest portion only 1-2 facets wide
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Thorax
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Red flour beetle has a curved-sided thorax
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confused flour beetle has a straight-sided thorax
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Antenna
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The last three antennal segments of the red flour beetle are much broader than the previous segments
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The antennal segments of the confused flour beetle gradually broaden
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Life Cycle
- Females lay between 300-400 eggs in their 5-8 month adult lifespan.
- Both stages i.e. larvae and adult can cause significant damage to grains that are already damaged physically or by the action of other pests.
- Adults move quickly and rapidly run for cover when disturbed. They can be found at the surface or deep within grain stores.
- Adults are able disperse over short distances through flight.
Detection methods
Pitfall traps baited with food such as carob beans, ground nuts and cereals can help detect individuals when their numbers are low. At higher densities holes and tunnels in grains and seeds can be seen as can the adults and larvae as well the dust created by their feeding activities. The eggs that stick to storage containers can be detected and there may be a pungent odour at high densities.