Fear no Weevil; Identification & Infestation Signs of Stored Product Insects Previous item Seasonal Pest Watch ... Next item Solar Panel Bird Proofing...

Fear no Weevil; Identification & Infestation Signs of Stored Product Insects

Grain Weevils, also known as Wheat Weevils,  and Grain Beetles, also known as Flour Beetles, are often collectively known as Stored  Product Insects (SPIs). They are frequently found throughout the UK and are considered as pests due to the damage and contamination they cause to stored products such as flour, grains, porridge oats and rice bran.


The most common species of Grain Beetle are the Rust Red Flour Beetle (Tribolium Castaneum) and the Confused Flour Beetle (Tribolium Confusum).  They are small reddish-brown in colour, measuring around 3-4mm in length.

Both species have the ability to fly, however they rarely do so. Adult Grain Beetles can live for over a year and produce up to 5 generations during their life span. Their eggs stick to the particles in flour or other food stuffs, which hatch into yellow-brown larvae, around 6mm in length. The process from egg to full adult takes around 3-9 weeks, and adults can live for up to 20 months.

The Grain Weevil (Sitophilus Granarius) is black to dark reddish-brown colour, has a shiny, oval/ cylindrical shaped body and grows to around 2-3mm long.  Unlike the Rust Red Flour Beetle and Confused Flour Beetle, the Grain Weevil cannot fly. Adults can live up to 8 months if conditions are warm and favourable.

Signs of a Weevil Infestation

As their name suggests, Grain Beetles and Grain Weevils can be found in stored grain, and other dried food products. Look out for the adult insects in your cupboards, and damage to raw foodstuffs, including any damp or mould, as infected grain often becomes warmer affording the ideal conditions for mould growth.  Grain Beetle larvae are very active, so you may see them crawling around in your flour or cereal!

Tribolium castaneum

What should I do if I discover a Weevil Infestation?

Any food that has been infested will be rendered unfit for consumption due to cast skins, pupal casing and secretions from the insects https://bpca.org.uk/pest-aware/spi-control-how-to-get-rid-of-and-prevent-stored-product-insects-bpca-a-z-of-pests/240955.  Immediately remove all infested food stuffs from your cupboards and dispose into an outside bin, then clean the area thoroughly.  As Grain Beetles and Grain Weevils are notoriously difficult to remove completely, Avon Pest Control recommend that you contact a professional pest control service who will use the appropriate insecticide to deal with your pest problem.  Grain Weevils lay 2-3 eggs per day, and Grain Beetles lay up to 10 eggs per day, so be sure to act fast!

What should I do if I discover a Weevil Infestation? - Life cycle wheat weevil

Insect Wheat weevil (Sitophilus granarius).

Prevention is Better than Cure

To help reduce the risks of infestation, ensure you:

  • Check stored foods regularly for signs of infestation
  • Try not to buy stored foods with damaged packaging
  • Use food within the best before and use by dates
  • Store foods in airtight containers
  • Try to keep food cool and dry at all times, as breeding in grain can only occur if there is warmth and moisture.

If Grain Beetles and Grain Weevils are causing chaos in your cupboards, call Avon Pest Control today on 01926 632 929 or 01789 293 463 or click here to request a call back.  Our qualified, responsible technicians will provide friendly, expert advice and deal with your pest problem for you.

Avon Pest Control was established in 1991.
We have been Serving the Community for over 30 Years!

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