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Some people are finding to their dismay that their food cupboards and especially dry goods such as flour, milkpowder, sugar or semolina, have become infested with tiny grey insects. They naturally, but wrongly assume that the products themselves are at fault. The purpose of this leaflet is to explain the presence of these insects, known as psocids and to tell you how to prevent them.

What are psocids?

Psocids are common but harmless household pests, smaller than a pinhead (usually about 1-1.5mm long) that are attracted to dry powdery type foods. They do not like the light but prefer to live in dark, warm, humid places such as the folds of packaging in food cupboards.

They can live for about six months and in that time a female will lay up to 200 eggs.

They are not caused by poor hygiene, they are just as common in scrupulously clean homes as they are in the not-so-clean.

At the same time, research has shown that the sorts of psocids (there are many different types) found in homes are never found where food is produced. So they are very unlikely to be brought into the home in foods.

So what causes them?

They are always associated with high humidity. It could be caused by new plaster drying out, it could be condensation from not having enough ventilation in the kitchen, it could be a leaky water pipe. There are many reasons but you can be sure that if you have psocids, you have humid conditions.

How are they prevented?

Always keep your dry foodstuffs, cereals and the like, in a cool, dry, well ventilated place.Clean out your cupboards regularly but if you use water, always make sure that they are completely dry before you put the food back. When you are cooking or boiling the kettle or even just using the washing machine or tumble drier, make sure
that the kitchen is properly ventilated.

How do you get rid of them if they appear?

Remove the affected food immediately and dispose of it outside. Check everything else in the cupboard. Food in cans and bottles will still be all right but make sure that there are not insects hiding under the labels. Treat the infected area with a good household insecticide which is suitable for use near food. Clean out all the dust and crumbs and then make sure the cupboard is completely dry. Having done that, find the cause of the humidity and cure it.

Date of last review: 01 September 2015