Pantry pests: weevils, flour moths and mice in the cupboard

Open a bag of flour, see something move, and it is hard not to feel a bit betrayed by your own pantry. It happens in clean kitchens all the time. Insects that live in stored food are common, they almost always arrive inside a packet from the supermarket or bulk bin, and they are easy to get rid of once you know what you are looking at.

Mice are a different matter. We will come to them.

Who is in the cupboard

The insects that infest dry food at home fall into two groups: moths and beetles. The University of California’s integrated pest management programme has a clear guide to pantry pests with photographs of each. In short:

Meal moths. The most common is the Indian meal moth, a small moth with reddish-brown, coppery outer wings. You usually see the adults first, fluttering out of the pantry in the evening. The damage is done by the larvae, small whitish caterpillars that leave silky threads and webbing through flour, cereal, nuts, dried fruit and chocolate. Clumped muesli held together with fine silk is the classic sign.

Beetles and weevils. Several small beetles, including flour beetles and sawtoothed grain beetles, wander through flour, grains, pasta, spices and pet food. Weevils, with their long snouts, mostly attack whole grains such as rice. You see the adults themselves, tiny and brown, walking across the shelf or floating in the rinsing water.

What to bin, what to freeze

Start by emptying the whole pantry onto the bench. It is a dull job and the only one that works.

• Bin anything with visible insects, larvae or webbing. Seal it in a bag and put it straight in the outside rubbish. Do not compost it, and do not try to sieve it and carry on.
• Check every other dry packet of flour, grains, pasta, cereal, nuts, seeds, dried fruit, spices, cocoa, chocolate, crackers, dried pet food and bird seed. Look at seams and folds; that is where larvae shelter.
• Freeze anything you want to keep but are unsure about. A few days in the freezer is the usual home approach for flour, grains and nuts that look clean but sat near an infested packet. The University of California guide also suggests storing rarely used flours, spices and grains in the freezer if you have room, which keeps them out of reach entirely.

Clean the shelves properly

Vacuum the shelves, corners, cracks and the joins where shelves meet the wall, then empty the vacuum outside. Wipe everything with warm soapy water and let it dry. You do not need insecticide inside a pantry; cleaning and sealing are what work, and spraying near food is a poor idea.

Pantry pests can live for weeks without food, so expect to see the odd straggler for a little while. Keep checking.

Glass beats plastic

The most useful change you can make is to move dry goods out of their bags and into glass jars or hard containers with sealing lids. Larvae can chew through thin plastic and paper, and a folded-over bag is no barrier at all. A sealed jar does two things: it keeps insects out of clean food, and if a new packet does bring something home, it keeps the problem inside one jar where you can see it.

Other habits that help:

• Buy smaller amounts of things you use slowly, especially wholemeal flours, nuts and bulk-bin goods.
• Use the oldest first. Put new packets behind old ones.
• Look before you tip. Check a new bag before adding it to a half-full jar.
• Keep pet food and bird seed sealed too. They are a favourite and often stored in the same cupboard.

Mice: a different kind of problem

Mice leave clear signs: small dark droppings like grains of rice along shelves and at the back of cupboards, gnawed corners on packets and boxes, shredded paper, and sometimes scratching in the walls at night. Unlike moths and beetles, they do not arrive in a packet. They come in through the building.

That is why mice are where a pantry problem becomes a building problem. The University of California’s house mouse guide notes that mice can squeeze through openings as small as about 6 mm, roughly a quarter of an inch, and recommends sealing gaps with wire screen or coarse steel wool that mice cannot chew through.

What we would do:

1. Clear and seal the food. Everything in glass or hard containers. Mice cannot get into a sealed jar.
2. Clean up droppings carefully. Wear gloves, dampen the droppings with disinfectant rather than sweeping them dry, wipe them up with paper towels and bin them, then wash your hands.
3. Find the way in. Look behind the oven, under the sink, where pipes and cables pass through walls, and at gaps around the back of cupboards and the hot water cylinder.
4. Set traps along walls and in dark corners where droppings are, which is where the University of California guide suggests placing them.

Winter is when rats and mice most often move indoors, a point Tenancy Services makes in its guidance on pests. If you rent, that page also explains who is responsible for what.

When to call someone

Insects in the pantry are a cleaning job you can do yourself. Call in a licensed pest controller, or talk to your landlord if you rent, when:

• mice or rats keep coming back after you have sealed the food and set traps,
• you can hear activity in the walls or ceiling,
• you find signs of rats rather than mice, such as larger droppings or gnawing on wiring or timber,
• or you cannot find or reach the way in.

A good pest controller will want to find and seal the entry points, not only set bait. That is what keeps the cupboard clear next winter.