Fear no weevil: identification and infestation signs of stored product insects

Written by Avon Pest ControlFirst published 27 September 2021Updated 9 November 2026

Weevils, flour beetles and the other small insects that live in dry food are known together as stored product insects. They are common in UK kitchens, they spoil the food they live in, and in most homes they can be cleared without any insecticide at all.

The short version

• Stored product insects live inside dry foods such as flour, rice, oats, pasta, cereals, spices and pet food.
• The cure is finding every infested item, binning it and cleaning the cupboard thoroughly.
• Airtight containers and checking packets when you buy them stop most problems starting.

Identification

The ones you are most likely to find at home:

• Grain weevils are 3 to 5mm long, dark brown to black and slim, with a distinctive long snout projecting from the head. The grain weevil cannot fly. The closely related rice weevil, which is slightly smaller and often has four faint orange spots on its back, can.
• Flour beetles (the rust-red and confused flour beetles) are 3 to 4mm long, flattened and reddish-brown, with no snout. See our flour beetles guide for more on them.
• Biscuit beetles are small, rounded and reddish-brown, and are often found in spices, dried herbs and biscuits.
• Saw-toothed grain beetles are very slim and dark brown, with a row of tiny teeth along each side of the body behind the head.

Weevils and flour beetles live differently. A female weevil chews into a whole grain and lays an egg inside it, so the larva develops hidden within the kernel and the adult chews its way out. Flour beetles cannot attack sound grain and live in flour, broken grains and processed foods instead.

Signs of a weevil infestation

• Adult insects in packets, on shelves or walking up cupboard walls and doors.
• Small round exit holes in grains of rice, wheat or other whole grains.
• Larvae moving in flour or cereal, or fine dust collecting at the bottom of a packet.
• Flour that looks greyish, clumps together or smells musty.

In large bulk stores, infested grain can heat up and become damp enough for mould to grow. In a kitchen cupboard the quantities are too small for that, and the insects themselves are the sign to look for.

What should I do if I discover a weevil infestation?

Food that insects have been living in is spoiled by their droppings, cast skins and dead bodies, and should not be eaten. Work through it like this:

• Empty the cupboard and check every dry product, not just the one where you saw insects. Infestations spread from packet to packet.
• Bin anything infested in a sealed bag in an outside bin.
• Freeze anything you are unsure about for a few days in a sealed bag. That kills all stages, including eggs and larvae hidden inside grains.
• Vacuum the empty cupboard, including corners, shelf supports and crevices, then wipe it down. Spilled flour and grains keep a population going.
• Do not spray insecticide in cupboards where food is kept. It is not needed once the food source has gone, and it risks contaminating the food you put back.

Keep an eye on the cupboard for a few weeks. A few stragglers are normal. A steady stream means a source has been missed.

Prevention is better than cure

• Check packets when you buy them, and avoid any with damaged packaging.
• Store flour, rice, cereals and similar foods in airtight containers.
• Use older stock first, and do not top up containers with new food on top of old.
• Keep cupboards clean, cool and dry.
• Check pet food and bird seed, which are a common source and often stored in warm utility rooms.

When to call us

Most domestic infestations are over once the source is found and the cupboard is cleaned. Call us if insects keep coming back after that, as they may be breeding in spilled food behind units or under appliances, or if you run a food business, where stored product insects are a food safety matter and inspectors will expect a documented response. We find where they are breeding and agree with you what needs to be cleared, and we only treat areas where it is safe and useful to do so.

Flour beetles → Food businesses →