Protecting food stores from pests and moisture

Pests need three things: access, food and hiding places. Pantry moths often lay their eggs in packages or in cracks in shelves; the caterpillars eat their way through the stock and leave fine webbing. Pantry beetles are so small that they crawl through folds and seams of bags. Mice gnaw through paper, cardboard and thin plastic.

Tight, hard containers made of glass, metal or thick food-grade plastic with a well-closing lid deny them access. If an infestation does get into one package, it stays in that one container and does not spread through the whole cupboard.

Mould needs mainly moisture and warmth. Dry goods absorb moisture from the air. On cold outer walls and cold floors condensation can form – like on a cold bottle that steams up. A cool, dry and dark place slows mould and also slows the development of insects.

Protection starts when you shop: check packages for holes, webbing or crawling insects and store only undamaged ones. After opening, put flour, rice, pasta, sugar and nuts into jars or tins with tight lids and label them with contents and date.

The storage place should be cool, dry and dark, not directly on the floor and not against cold outer walls. Keep it away from cleaning products and fuels. Do not pour new stock on top of old; use up the old container first and clean it before refilling.

About once a month a quick look is worthwhile: webbing, larvae, beetles, gnaw marks, droppings, a musty smell or damp patches? Wipe the shelves at the same time and remove crumbs – they are food for pests. Some households put flour or nuts in the freezer for a few days before decanting to kill any insect eggs, and then store them dry and sealed.

Mould on grain, nuts, bread or dried fruit is not cut away or sifted out – the whole item goes. Moulds grow into the food with fine threads, and some produce toxins, called mycotoxins, which are invisible and not reliably destroyed by cooking.

Insecticides and baits do not belong near food. For rodent infestations, call in professionals. Food that has come into contact with mouse droppings or urine is discarded; clean surfaces thoroughly. A heavy infestation in the building is a job for a pest control company.

If you discover an infestation, dispose of the affected food sealed, for example in a tied bag in the outdoor bin. Then check all nearby containers, because moths and beetles move around. The shelf is emptied, cleaned thoroughly and dried, especially in corners and cracks.

Then look for the cause: an open package, a leaky tin, a damp wall, crumbs behind the shelf? Fixing the cause usually solves the problem. Sifting infested flour and using it anyway is no solution – droppings, webbing and eggs partly remain in it.

Official preparedness guides such as the US agency FEMA's “Are You Ready?” recommend storing food cool and dry and putting opened packages into tightly closing containers. Which pests occur depends on region and building – the approach stays the same: sealed, dry, checked.

A pleasant side effect: if you keep your stores in labelled, see-through containers, you can see at a glance how much is left. That makes rotating and restocking much easier too.