Home-Stored Food Pests

What is a food pest? One of the most common household problems – insects living in pantries, devouring and contaminating stored natural products. While these insects usually present little to no health hazard, some species (notably carpet beetles) can induce irritations and allergies.

As defined by the Official site of the London Borough of Croyden, food pests are rats, mice, beetles, cockroaches, ants, flies, and birds.


Quick Facts:

  • Nearly all dried natural products are susceptible to infestations. Such as grains, flours, nuts, spices, powdered milk, packaged herbs and dried fruits. Including some non-food items as pet food, birdseed, dried plants, rodent baits and etc.
  • Stored food insects can infest opened products as well as unopened paper, thin cardboard, plastic, foil or cellophane-wrapped packages.
  • All stages (egg, larvae, pupa and adult) may be present simultaneously.
  • Insect pests that attack stored food are usually beetles or moths.
  • Regardless of where we find them, the key to solving the issue is to locate the source of infestation.

Why are Pests Food Safety Hazard?

Food might get contaminated with:

  • fur
  • droppings or urine
  • eggs/larvae or dead adult insects
  • dirt picked up on their way

Learn the difference between mice and rats droppings.

Diseases and health hazards pests can cause:

  • Salmonella
  • E. coli
  • Staphylococcus
  • Leptospirosis
  • Parasitic worms
  • Toxoplasmosis
  • Listeria
  • Cryptosporidium
  • Fungi

Learn what diseases rodents carry and can transmit to people.
See what other health problems can pests cause.


Identification of common stored food pests:

1. Indian Mealmoths (Plodia Interpunctella)

These beetles are the most common stored product pests. Adults are 8-10mm long, with the outer half of their wings are bronze, copper, or dark grey in colour, while the upper half is yellowish-grey, with a dark band at the intersection between the two. The adult moths do not actually damage packaged goods. Its larvae (caterpillars), known as waxworms (like those of its relatives), are a common grain-feeding pest found around the world. They spin silk webbing over the surface of their food, thus if the infestation is present food will seem to be webbed together. When the larvae finish their development, they often crawl onto walls and ceilings, making their full extermination harder.

Signs of infestation: larvae or webbing on products; adults flying about; larvae or pupae in cupboards, on ceilings or walls;

2. Flour Beetles (Tribolium confusum and T. castaneum)

They are common pests and are also widely used as laboratory animals. Adults are 3/16 inch long, reddish-brown and elongated oval in shape. The flour beetles typically consume wheat and grains, but also other natural products such as chocolate, dried fruits and nuts. They are adapted to survive very dry conditions and can withstand even higher amounts of radiation than cockroaches. There are two species of flour beetles – the red flour beetle, common in households and the Tenebrio beetle that is a major pest in the agricultural industry. These insects are also highly resistant to insecticides. Their full-grown larvae are known as mealworms.

Signs of infestation: larvae and/or adults on the infested products; adults on nearby surfaces; small pieces of cracked grains;

3. Sawtoothed Grain Beetles (Oryzaephilus surinamensis)

These beetles are slender, dark brown, about 1/10 inch long beetles. Easily identified by their saw-like teeth running down the side of the thorax. They can be found in different food items, like dried fruit, cereals, nuts, macaroni, seeds and dried meat. The adults can fly but rarely do. The beetle lays its eggs on foodstuffs about 6-10 per day, larvae are a cream-coloured, slender and about 1/8 inch long, but rarely noticed.

Signs of infestation: larvae and/or adults on infested goods; adults on nearby surfaces;

4. Drugstore Beetles and Cigarette Beetles (Stegobium panicum and Lasioderma serricorne)

They are oval, brownish beetles, about 1/5 inch long also known as bread or biscuit beetles. Their bodies are curved and covered with fine hair. Both species fly and can be found around windows. The drug store beetle is slightly larger than the cigarette beetle and their antennas also differentiate. They are usually found in spices (particularly red pepper), tobacco, bread, flour, meal, even paper products, including books. The female can lay up to 75 eggs at once. The larvae are responsible for most of the damage this species can cause.

Signs of infestation: larvae and/or adults on the infested goods; adults on nearby surfaces.

5. Spider Beetles (family Ptinidae)

They resemble small spiders with round bodies, long, slender legs (two pairs of three) and lack wings. Both larvae and adult are scavengers that can live off any kind of natural products including grains, nuts, books, cereals, animal products of any kind, flour, spices, dried fruit and vegetables, seeds, textile fabrics and dried excrements. Spider beetles are most active at night or in dark locations. They also prefer damp locations and foodstuffs that are spoiled by moisture. You can find them within walls, attics, basements, in the cracks of wooden floors and in the nests of birds and rodents.

Signs of infestation: larvae and/or adults on the infested goods; adults on nearby surfaces.

6. Bean Weevils (Acanthoscelides obtectus)

Or seed beetles are granivores, that typically infest various kinds of seeds or beans, living most of their life inside a single seed. They’re blotched light or dark brown in colour, about 1/8 inch long and they lack the conspicuous snout, typical for weevils. Their bodies are broadly oval with small heads somewhat bend under. The family includes about 1,350 species found worldwide.

Signs of infestation: beans or any kind of grains with holes; adults on nearby surfaces.

7. Wheat Weevils (Sitophilus spp.)

Also known as a granary or grain weevils, can be found all over the world and are a common pest that causes great damage to stored grains. These insects are slender, with an elongated snout and chewing mouthparts. Depending on the grain, they vary in sizes. The adults are reddish-brown in colour. The females lay many eggs, while the larvae eat the inside of the grains. Larvae are legless, humped and white with a tan head, found only inside whole kernels or seeds. Pupae have the same snouts as adults. These weevils attack only whole grains or seeds, leaving small round exit holes in the infested goods.

Signs of infestation: grains and seeds with small round holes; adults nearby infested goods;

8. Cockoaches

Cockroaches are a common pest not only in the UK but worldwide. They can infest your bathroom, your basement, your attic, but most of all – your kitchen. Why? Because there’s food there. They can get into your garbage, but they will also get inside of your cupboards and attack your home-stored food. If there’s easy access to it, you can bet they will get there. Even the smallest hole or gap in your cupboards will be enough for them to squeeze through and munch on your pasta, sugar, cookies, or anything else you haven’t closed properly.

Signs of infestation: seeing live cockroaches inside cupboards, pantry, or even inside poorly closed packaged foods; seeing cockroach droppings inside pantry or cupboards.

Read more about common house cockroaches and their eggs.

9. Ants

If they sense the food and can get to it- they will. No matter how far from their entry point it is, they will form an efficient and quick organised colony to get as much food as they possibly can.

Signs of infestation: seeing a long colony of ants heading for your pantry; seeing a bunch of ants inside of your opened packaged foods (no colony of ants necessary); food is missing for no apparent reason.
Read about the most common ants in the UK.

10. Fruit flies

Fruit flies are the tiny brown-reddish insects that you see flying in and out of your fridge, pantry or garbage. They are attracted mostly to fermented fruits, vegetables, sugary foods and liquids, and food scraps. You will usually find them accumulating near your garbage, over-ripe fruits or vegetables, honey or sugar stains, juice bottles.

Sings of infestation: the live fruit flies.

Food Pest Control

Most common foods that get infested by various insects

  • Cereals, flour, rice, pasta
  • Cookies and chocolate
  • Nuts and seeds
  • Spices and herbs
  • Fruits and dried fruits
  • Not so often: tea, vegetables, coffee creamer or powdered milk, cocoa

Prevention

  • Store food in air-tight glass, metal or heavy plastic containers (especially if the food is going to be stored for a long period);
  • Check pantries for spilled food regularly;
  • Check opened and unopened packages for signs of infestation (webbing, larvae);
  • Washing areas with heavy chemicals will not prevent insect infestation;
  • Place sticky traps with insect pheromones in cupboards;
  • Check and clean areas where pet food and birdseeds are stored;
  • Thoroughly clean crack and corners with a vacuum cleaner; see our checklist for a fully pest-proofed home;
  • Practice “FIFO” (First In – First Out), hence always use up your oldest materials before opening new packages;

Pest Elimination

  • Throw away any infested food or natural goods;
  • Use a vacuum cleaner to thoroughly clean pantries, shelves and cabinets, especially any cracks, corners and spots where the infestation occurred. After, discard the vacuum cleaner bag to prevent re-infestation.
  • It is not unusual to occasionally see Indian meal moth flying around for as long as 3 weeks after the infestation. However, if after the 3 week period moths continue to be present that indicates an infested food source which has not been discovered.
  • If you’re not sure whether a product is infested or not, you can place it in the freezer at 0 degrees for at least 4 days. Or you can place it in an oven at 130 degrees for at least 30 minutes. These temperatures will kill any eggs or insects that may be present.

Insecticides

The use of insecticide sprays is not advised for controlling insects in stored food pantries. It provides little additional influence and has no effect on insects within food packages. Any control outside of packages is temporary unless the source of infestation is found and eliminated.

Also, the use of insecticide in kitchen areas requires effort that is not corresponding to the result. First, it’s necessary to remove dishes, glasses and food so they are not contaminated. Time is needed to allow the spray to dry before items can be returned. Never apply insecticides in a manner that allows contact with food or food utensils. Note that if you have a serious problem with any of the above homes-stored food pests, you shouldn’t wait too long before you call professional pest controller.

Resources:
https://extension.umn.edu/insects-infest-products-and-houseplants/pantry-pests-insects-found-stored-food
https://www.organiclesson.com/6-ways-to-instantly-get-rid-of-gnats-at-home/
http://www.foodsafetysite.com/educators/competencies/general/pests/pest1


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