Control Of The Meal Moth

The main pest species of stored food include the Flour or Meal Moth, the Mediterranean Flour Moth and the Indian Meal Moth.

The larvae of these and several other species feed on cereals and cereal products and frequently destroy or damage large quantities of food in granaries and flour mills. They also attack nuts and dried fruit.

Moths are extremely delicate insects, and the most common species in the UK have a wingspan of about 20-40 mm. They are usually more or less brownish in colour, although the wings of some species are distinctively patterned with contrasting dark and pale areas, and sometimes with reddish or green-tinged patches. The forewings are generally narrow and the hind wings somewhat broader, and both pairs of wings bear relatively short fringes.

Adult meal moths cause no direct damage and it is only when the insects are in the larval stages (or caterpillars) that they attack our food stuffs.

Caterpillars of meal moths are generally whitish or pale-yellowish in colour with few distinguishing features, but often they can be recognised by their vigorous wriggling when disturbed. They feed on a wide variety of materials, including grain and other stored food products, and many of them live in silken tubes and tunnels.

It is always advisable to keep household foods such as grain, cereals, flour, nuts, etc., in well sealed plastic or glass containers - this not only keeps out vagrant moths, but also prevents the spread of insects which might be introduced accidentally (often as eggs and/or larvae) with newly purchased goods.

Preventative Control Measures

• The best method of avoiding problems with stored product pests is good sanitation. Be sure that the areas where food is prepared, eaten, and stored are cleaned regularly. Avoid leaving spilled food or food exposed in open packets and containers as this attracts and harbours meal moths. Regular cleaning of workspaces, including behind appliances and inside drawers ensures that the risk of an infestation is drastically reduced.
• Buy dry food stuffs intend for storage, such as cereals, grain, meal, flour, biscuits, nuts, dried fruits, etc., only in quantities that you will use in a reasonable length of time. Materials stored for long periods (e.g., six months or more) are often the source of serious infestations. Pests can develop here without being noticed. In any event, routinely check all stored food products, especially those that go extended periods of time between use.
• Meal moth caterpillars can chew their way into cardboard boxes and thin polythene bags. Always keep stored materials in tight-fitting containers, preferably of glass, metal or tough plastic. If an infestation should occur under these conditions (possibly introduced with newly purchased goods), it probably will be confined to a single jar or container and easily eradicated by discarding the contents.
• Glass jars should have rubber seals, and metal or plastic containers should have tight-fitting lids. Dried pet foods are one of the most frequent stored products attacked by moth pests, so it is wise to be especially attentive to the storage of these foods. If you find a container with infested food, place the food container in a home freezer for about a week, which should kill any livestock that is present. Then discard the infested material and wash the container thoroughly before reusing.
• If a moth infestation becomes apparent, locate the source immediately and get rid of it. If you act early enough, this may be the only material infested. Examine unopened food packages thoroughly. If there is the slightest suspicion throw it out. If the material appears uninfested and you prefer to keep it, then at least transfer it to a sealed glass, metal or plastic container and inspect it frequently.
• Use a vacuum cleaner to remove debris from cracks and corners of infested storage areas. Also clean all nearby areas, especially spills and crumbs behind and alongside appliances. Scrub the storage space and vicinity with very hot water and a good household kitchen cleaner or strong detergent solution. Allow to dry thoroughly before replacing food stuffs.

Insecticide control of household food pests is not generally recommended and can only supplement the more important steps of sanitation. Only use insecticides well away from areas where food is stored, prepared or eaten and then only as a last resort.

The control measures described above for Meal Moths are also applicable to Grain Beetles and Flour Beetles, as well as other domestic beetle pests that likewise attack dried food products.