Common species of pests in food

Pests found in food covers a large variety of insects, including beetles and moths.

Learn more below about common species of Stored Product Insects (SPIs) found in Fiji.

Australian spider beetle

(Ptinus Tectus)

Appearance

Covered in brown and golden hairs, the Australian spider beetle has a spider-life appearance and adults grow to an approximate 2.4 – 4mm in length.

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Lifecycle

Australian Spider Beetles live for up to 3 – 4 months at 20 - 25°C.

Feeding Habits

Larvae are often found feeding on miscellaneous debris, and the Australian Spider Beetle possesses the ability to bore into various inedible materials prior to pupation. Active in dark, damp places, the Australian Spider Beetle is often associated with bird nests.

Booklice

(Various species - Liposcelis bostrychophila, Lepinotus patruelis)

Appearance

  • Adult — Size varies according to species. 1/16" - 1/8" long. Pale yellow–brown to dark brown in colour. 
  • Nymphs — very small, often appear transparent. No larval stages.
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Lifecycle

  • Liposcelis bostrychophila — prefers high temperatures 25–30°C. 
  • Lepinotus patruelis — will breed at 5–15°C.

Habits

  • Liposcelis bostrychophila — Common in homes. 
  • Lepinotus patruelis — Common in factories and on pallets.

Broadhorned Flour Beetle

(Gnatocerus cornutus)

Appearance

An approximate 3.5 – 4.5mm in length, male broadhorned beetles have two enlarged mandibles on the head, giving the appearance of horns and thus their name. Females are very similar In appearance to the confused flour beetle.

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Lifecycle

With temperature limits of 15 - 32°C, broadhorned flour beetles cannot complete their life cycle below 10°C.

Feeding Habits

Feeds on flour, dough, semolina etc. Moth eggs and larvae may supplement the broadhorned flour beetle diet.

Cheese mites

Appearance

Cheese mites have soft, hairy cream white bodies with 8 hairless legs and adults grow up to an approximate 0.5mm in length.

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Lifecycle

The cheese mite favours warm, moist conditions and eggs mature in 10 days at room temperatures. Females can lay up to 900 eggs in a lifetime at a rate of 20 – 30 a day. Adult cheese mites can live for up to 60 – 70 days.

Feeding habits

With a preference for old cheese to young cheese, these mites also feed on nuts, dried eggs, fruit, flour and tobacco. Cheese mites are capable of contaminating foods to cause skin or gut irritation.

Cigarette beetle

(Lasioderma serricorne)

The Cigarette beetle is a very common commercial pest.

Appearance

  • The Cigarette Beetle is about 2-4mm in length.
  • The adult is whitish in color, with the head dark brown to tan, and are densely haired.
  • The cigarette beetle closely resembles the drugstore beetle.
  • The cigarette beetle has the head bent down nearly at right angles to the body giving it a humped back appearance when viewed from the side.
  • The larvae are about 4 mm long and somewhat bent.
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Lifecycle

  • The adult beetles live from 2 to 4 weeks and during this time the females may deposit between 10-100 eggs.
  • The eggs are laid loosely on the infested material.
  • The larval period usually ranges from four to five months, but under very favorable conditions the development from egg to adult may occur in 6 to 8 weeks.
  • When the larvae are fully grown, pupation occurs and they remain in this resting stage for 12 to 18 days.

Habits

  • The Cigarette Beetle feeds off tobacco, dry stored food products, spices, seeds, grains and dried plant material.
  • They have also been reported in rice, dried potatoes, paprika, raisins, grain-based mouse bait and dried straw flowers.
  • Adult beetles often wander away from infested materials and may be found throughout the area.

Coffee Bean weevil

(Araecerus fasciculatus)

Appearance

  • Adults: 1.5-4mm in length. 
  • It is a dark brown beetle with light brown spots and long antennae. 
  • The footless, slim larvae are curved and hairy and grow to a length of 5-6mm.
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Lifecycle

  • The beetle flies to fields and lays its eggs on damaged cobs. 
  • The larvae bore into coffee beans in which they pupate.

Habits

  • They mainly infest corn, cocoa, coffee beans, dried fruits, nutmegs, ginger etc.

Confused Flour beetle

(Tribolium confusum)

The confused flour beetle was named because of the confusion over its identity. It is a very common commercial and pantry pest.

Appearance

  • The confused flour beetle is 3-4 mm in length, the larvae are about 6 mm long.
  • The adult is red-brown in color and the larvae are a light honey colour and about.
  • It resembles the rust-red flour beetle, except for the antennae which is four segmented and gradually thickens towards the tip - another slight difference is in the shape of the thorax.
  • The sides of the rust-red flour beetle are curved, whereas the thorax of the confused flour beetle is straighter. It has well developed wings but seldom flies.
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Lifecycle

  • Female lays between 400 - 500 eggs, with peak oviposition occurring during the first week.
  • Adults may live longer than 3 years, and females may lay eggs for more than a year.
  • Eggs are deposited directly in flour, other food material, or attached to the surface of the container. They are white or colorless and covered by a sticky material to which flour can adhere.
  • Eggs hatch in 3 - 5 days at 32 - 35°C. Larvae burrow into kernels of grain but may leave their burrows in search of a more favorable food.

Habits

  • Feeds off grain, flour, and other cereal products, beans, cacao, cottonseed, shelled nuts, dried fruit, dried vegetables, drugs, spices, chocolate, dried milk and animal hides.
  • They cannot feed on whole grain, but can feed on broken kernels that are usually present.

Dermestes beetle

(Dermestes beetle)

Appearance

  • Adult – 1/4"–3/8" in length. Black with a whitish band across the fore–part of the elytra. 
  • Larva – comet shape. Quick moving. Brown in colour and hairy. Migrate to pupate in solid material.
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Lifecycle

  • 2–3 months at 18–25°C.

Habits

  • Feeds on various animal products including cheese.

Drugstore beetle (Biscuit beetle)

(Stegobium paniceum)

The drugstore beetle (also known as the Biscuit Beetle) gained its name because it was frequently found feeding on drugs in pharmacies many years ago. Now, they are customarily found infesting all types of dry stored food products, spices, seeds, grains and dried plant material.

Appearance

  • Approx. 3 - 4 mm long, red-brown, oval beetles.
  • The larvae are small and white approximately 0.5 mm long.
  • The drugstore beetle is a red-brown oval-shaped beetle.
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Lifecycle

  • The adult beetles live from 2 to 4 weeks and during this time the females may deposit between 20-100 eggs.
  • The hatching larvae are 0.5 mm long and very mobile.
  • The larval period usually ranges from four to five months, but under favorable conditions the development from egg to adult may occur in 6 to 8 weeks.
  • When the larvae are fully grown, pupation occurs and they remain in this resting stage for 12 to 18 days.

Habits

  • It is not a major pest in stored grains but will attack spices, seeds, grains and dried plant material as well as packaging materials such as paper and cardboard.
  • They have also been known to feed on leather, wool, hair and books.
  • Their presence can be detected from pinhead holes in the infested items.
  • Packaging materials such as paper and cardboard are also attacked.
  • Since the drugstore beetle can fly well, the source of infestation can sometimes be hard to find.
  • The drugstore beetle is not a major pest in stored grains.

Flat Grain beetle

(Cryptolestes ferrugineus)

Appearance

  • Adult — About 1/8" in length. Flattened body with very long antennae. Light red to dark reddish brown. 
  • Larva — yellowish–white. 0.5mm long growing to 4mm when mature.
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Lifecycle

  • Prefers warm damp conditions. 69–103 days at 21°C, 26 days at 38°C.

Habits

  • Adults are winged but rarely fly. 
  • Feeds on cereals, dates, dried fruits and other commodities.

Flour mite/ Grain mite

(Acarus siro)

Appearance

  • Adult — 0.5 mm long. 4 pairs of legs. White or pale brown. Slow moving. 
  • Larva — 6 legged and 0.5 mm long. White in colour. Passes through two, 8 legged nymphal stages.
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Lifecycle

  • 9–11 days at 23°C and 90% relative humidity.

Habits

  • Under adverse conditions, may pass through a long and very resistant stage called a hypopus.

Foreign Grain beetle

(Ahasverus adena)

It is frequently associated with hot spots in farm-stored grain. Although primarily a fungivorous species. The presence of this insect in farm-stored grain is taken as a warning that the grain is beginning to spoil and become moldy.

Appearance

  • The adult Foreign Grain Beetle is light brown and is about 2 mm long.
  • They are similar in appearance to the saw-tooth grain beetle, but they lack the tooth-like projections and are somewhat broader.
  • Larvae are initially white and gradually darken as they mature. They rarely grow larger than 3 mm and have no forked process at the tip of the abdomen.
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Lifecycle

  • Adult females begin laying eggs around 3 - 4 days after emerging.
  • Mated males and females have an average lifespan of 159 and 208 days, respectively.
  • Eggs, which are laid singly or in clusters of two or three, hatch in 4 - 5 days.
  • Larval development is completed in 11 - 19 days. When ready to pupate, the larva constructs a chamber of food particles cemented together.
  • Pupation occurs after a prepupal period of 1 - 2 days, and adults emerge 3 - 5 days later.

Habits

  • The adults are long lived, fly well and run very rapidly.
  • This species occurs on a wide variety of foodstuffs, including grains, cereal products, oilseeds and their products, dried fruit, and spices.
  • It is a scavenger that feeds on molds, dead insects, and damaged foods.
  • On cereal grains, the embryo is a suitable food material. However, when found in large numbers they are probably feeding on molds present in the food.

Furniture mite

(Glycyphagus domesticus)

Appearance

  • Adult – 0.3–0.7mm. Hairy soft cream–white body with yellow/brown legs.
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Lifecycle

  • Egg to adult in 22 days at room temperature. 
  • Adult lives for approximately 50 days.

Habits

  • Capable of tainting foods and causing gut irritation. 
  • Commonly feeds on flour, cereals and fungi. 
  • Favours moist environmental conditions; common in damp poorly ventilated rooms.

Golden Spider beetle

(Niptus hololeucus)

Appearance

  • Adult — 1/8" - 3/16" in length. Ovoid abdomen with a pinched waist. Whole body covered in golden-yellow hairs. 
  • Larva — similar to Australian spider beetle.
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Lifecycle

  • 6 - 7 months at 20°C. Adults can live up to 9 months.

Habits

  • Sometimes linked to the damage of textiles in the domestic home. 
  • Adults appear in greater numbers in June/July and October/November.

Grain borer

(Prostephanus truncatus)

Appearance

  • Brown body colour. 1/16" to 3/16" in length. 
  • Antennae have 3 large segments at the end forming visible antenna clubs, reddish in colour. 
  • The humped thorax covers the head, its front rim has teeth–like indentations. 
  • Elytra (wing covers) are heavily punctated and drop off sharply at the back, giving the impression of a square end when seen from above.
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Lifecycle

  • The female lays an average of 10 eggs on a grain of maize and the hatched larvae bore into the grain. 
  • The larva undergoes up to 4 development phases and pupates inside the corn grain. 
  • Lifecycles can be quite short, in good conditions (25 days at 34 °C, 75% relative humidity) there are several generations per year.

Habits

  • Adult beetle is a pest of stored maize, but also infests other types of grain. Larva bores tubular passages into the grain, typically making one main tunnel with smaller ones branching off. 
  • Brought in from tropical Central America in cassava roots and tapioca products, as well as in starchy fruits and tubers.

Khapra beetle

(Trogoderma granarium)

The Khapra Beetle is considered to be the world's most destructive pest of stored grain and grain products. If left uncontrolled, this beetle can cover the surface of stored grain making it appear alive with crawling larvae

Appearance

  • The male is about 2 mm in length and the female is slightly larger (up to 3 mm).
  • Dark-brown beetle with yellow-brown to red-brown markings on the wing covers.
  • They are also covered with fine hairs which may trap dust, giving a dirty appearance.
  • The larvae are yellow to golden brown and reach a length of up to 5 mm. They are covered with thick, red-brown hairs with two tufts at the end of the abdomen.
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Lifecycle

  • Adults are short-lived, completing their adult life in one to two weeks.
  • Mating occurs almost immediately after adult emergence, with oviposition for one to six days following.
  • In ideal conditions the life cycle can be completed in as few as 30 days.
  • The female lays up to 125 eggs loosely in the infested material.
  • Eggs hatch in five to seven days.
  • The larvae undergo 4 - 7 molts, resulting in the shedding of numerous cast skins.

Habits

  • It is also considered to be a dirty feeder as it breaks or powders more grain than it consumes.
  • They also contaminate the grain with larval skins and setae which have been known to cause gastrointestinal irritation.
  • Feeds on rice, peanuts, dried animal skins, as well as its preferred natural foods such as wheat and malted barley.

Larder beetle

(Dermestes lardarius)

Appearance

  • Adult — 1/4"–3/8" in length. Black with a whitish band across the fore-part of the elytra. 
  • Larva — comet shape. Quick moving. Brown in colour and hairy. Migrate to pupate in solid material.
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Lifecycle

  • 2–3 months at 18–25°C.

Habits

  • Feeds on various animal products including cheese.

Leather beetle

(Dermestes maculatus)

Appearance

  • Adult — 6–10mm in length. Uppermost is black, underside is white.
  • Larva — as D. lardarius but with an orange stripe running down the length of the back.
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Lifecycle

  • 2–3 months at 18–25°C.

Habits

  • Feeds on various animal products and dried fish. Pupates in solid material, e.g. wood. 
  • The quantity of white on the underside may vary according to species. Adults fly readily.

Lesser mealworm

(Alphitobius diaperinus)

Appearance

  • Adults - 1/4" long. Newly moulted adults are reddish-brown turning black. 
  • Larvae - 5/16" long. Slender, segmented and worm-like with three pairs of tiny legs on the thorax and one abdominal proleg at the rear.
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Lifecycle

  • Females can lay up to at least 110 eggs a month and eggs hatch in 4-7 days. Larval development takes up to 7 weeks. Mature larvae seek a sheltered place to pupate for between 7 and 11 days. 
  • An adult beetle may live up to two years.

Habits

  • The beetles are attracted to poultry operations, which have ideal conditions for their development. The damage to insulation is carried out by lesser mealworms seeking a safe place to pupate because the darkling beetles prey on the lesser mealworms.

Maize weevil

(Sitophilus zaemais)

Also known as the Greater Rice Weevil. Maize Weevils are frequently regarded as primary pests of grain since they are able to infest otherwise undamaged grain.

They have also been seen to infest buckwheat, peas, acorns, chestnuts and cottonseed.

Appearance

  • It is about 2.5 - 4 mm long.
  • The head has a long slender snout.
  • Resembles rice weevil, only bigger and the red-brown spots on wing covers are more clearly marked.
  • It is a stronger flier than the rice weevil.
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Lifecycle

  • The egg, larva, and pupa stages of these weevils occur in the grain kernels and are rarely seen.
  • Females drill a tiny hole in the grain kernel, deposit an egg in the cavity, then plug the hole with a gelatinous secretion.
  • The egg hatches into a young larva which bores toward the center of the kernel, feeds, grows, and pupates there.
  • New adults bore emergence holes from the inside, then leave to mate and begin a new generation.

Habits

  • Both larvae and adults will feed upon grain.
  • Weevil-damaged grain can be readily recognised by the presence of large holes which are the exit holes of the emerging adults.

Fungus Beetles

(Family — Cryptophagidae)

Appearance

  • About 1.5mm (Plaster beetle) and 3.5mm (Fungus beetle).
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Lifecycle

  • Life cycle usually completed at 54 days but can live for up to 5 months in warm temperatures.

Habits

  • Fungus beetles may carry moulds from one commodity to another in damp warehouses. 
  • May contaminate food. 
  • Minor pests on damp plaster, particularly in newly–built houses. Also in mills and warehouses where they may infest damp foodstuffs.

Rice weevil

(Sitophilus oryzae)

Rice weevils are pests of stored grain and seeds.

Appearance

  • The adult rice weevil is 2.5 - 3.5 mm long and has a slender, hard-shelled bodies that appear pitted or scarred with tiny holes.
  • They are brown-black in color and possess a long slender snout.
  • Rice weevils have four faint red-brown spots on the back of the abdomen.
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Lifecycle

  • The adults live 3 to 6 months, infesting grain in the field.
  • The egg, larva, and pupa stages of these weevils occur in the grain kernels and are rarely seen.
  • Females drill a tiny hole in the grain kernel, deposit an egg in the cavity, then plug the hole with a gelatinous secretion.
  • The egg hatches into a young larva which bores toward the center of the kernel, feeds, grows, and pupates there.
  • New adults bore emergence holes from the inside, then leave to mate and begin a new generation.
  • Female rice weevils lay between 300 to 400 eggs, with the life cycle requiring about 32 days for completion. Two larvae can develop in one wheat kernel.

Habits

  • The adults can feign death by drawing up their legs close to the body, falling, and remaining silent when disturbed.
  • Emergence holes of the rice weevil are smaller than those of the granary weevil, and tend to be smooth and round.
  • There is generally no external evidence that the larvae have been eating and growing inside the seed until after about one month when the adult weevil chews through the seed coat and emerges.

Rust-red flour beetle

(Tribolium casteneum)

Is a very common commercial pest infesting a variety of grain and food materials. The rust-red flour beetle is frequently found in stored products in Australia.

Appearance

  • The Rust-red flour beetle is red-brown in color.
  • 3.0 - 4.0 5mm in length.
  • The antenna of the rust-red flour beetle is distinctly club-like, with a three segmented club and it has grooved wing covers.
  • The Rust-red flour beetle has well developed wings and has been observed to fly.
  • The larvae are a light honey color and about 6 mm long.
  • The head and a distinctive forked process at the tip of the abdomen are slightly darkened.
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Lifecycle

  • The female lays approximately 400 - 500 eggs, with peak oviposition occurring during the first week.
  • Adults may live longer than 3 years, and females may lay eggs for more than a year.
  • Eggs are deposited directly in flour, other food material, or attached to the surface of the container. They are white or colorless and covered by a sticky material to which flour can adhere.
  • Eggs hatch in 3 - 5 days at 32 - 35°C. Larvae burrow into kernels of grain but may leave their burrows in search of a more favorable food.
  • Larvae are fairly active but generally hide within the food, away from light.
  • Development time from egg to adult varies with conditions, however the average is 26 days at 32 - 35°C and >70% relative humidity (R/H).

Habits

  • When agitated or crowded, they may secrete chemicals called quinones. These chemicals can cause the infested feed to turn pink and have a pungent odor.
  • They have been reported in grain, flour, and other cereal products, beans, cacao, cottonseed, shelled nuts, dried fruit, dried vegetables, drugs, spices, chocolate, dried milk and animal hides.
  • They cannot feed on whole grain, but can feed on broken kernels that are usually present.
  • In general, fungi may play a significant role in the nutrition of rust-red flour beetles.

Cowpea Weevil

(Callosobruchus maculatuss)

Appearance

  • The moth has a wing expanse of 14-17 mm; when at rest, the wings folded to a roof over the body, it is 8-11 mm long.
  • The adult moth has brownish grey forewings crossed with two light bands.
  • The hindwings are paler and plain grey.
  • The caterpillars are whitish, yellowish or reddish (depending on nutrition) with brown head and neck shields. They grow to a length of 10-15 mm.
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Life Cycle

  • The female deposits about 100 eggs, singly or in small clusters.
  • The caterpillars cover the infested goods with webbing.
  • Pupation occurs in a cocoon.
  • The development period depends on warmth and nutrition. Depending on the season, complete development takes 2-6 months.

Habits

  • The Tobacco Moth feeds on cocoa beans and tobacco, but also infests nuts, dried fruit and cereals.
  • Adult moths do not feed.
  • The larval feeding cause the most damage due to contamination with excrement and cocoons is immense. Besides tobacco, the pest infests cocoa, nuts, dried fruits, coffee, corn maize, wheat and spice

Four Spotted Bean Weevil

(Bruchus quadrimaculatus)

Appearance

  • Adult 4mm long. 
  • Stout-bodied, shortened wing covers and a short broad snout.
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Lifecycle

  • The female lays eggs into stored beans or into seed pods in the field. 
  • When fully grown, the larvae form pupae in the eaten-out cavity of the bean. 
  • Young adults chew their way out of the beans, mate, lay eggs and begin a new generation. 
  • As many as six generations are produced in a single year.

Habits

  • The adults attack legumes either in storage or in the field and may completely destroy them. 
  • Breeding continues in stored products as long as the products maintain their nutritional value and the storage environment is warm.

Yellow mealworm beetle

(Tenebrio molitor)

Appearance

  • Adults – 3/4" long. They are shiny, dark–brown or black. 
  • Larvae are honey–yellow, they have a smooth, highly polished, shiny, elongate, hard, worm-like body, and can grow to 1 3/16" long.
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Lifecycle

  • Each female lays about 275–600 eggs singly or in clusters during the spring. 
  • They are white, bean-shaped and about 1/32" long and hatch into larvae in 4 to 14 days. 
  • The pupal stage lasts 7 to 24 days during the spring. Pupae are first white, turning yellow, and are not enclosed in a cocoon. 
  • Adults emerge in the spring or early summer, living for two to three months.

Habits

  • They are highly resistant to cold temperatures. 
  • It is an important post–harvest pest and occurs spread all over the world. 
  • Adult beetles are attracted to night-lights, are strong fliers, and are found in dark places.

Fur Beetle

(Attagenus pellio)

Appearance

  • Adult — 3/16"–1/4" long. Elongate oval. One small patch of white on each wing case, otherwise red–brown to black. 
  • Larva — 1/4" long. Long orange tufts of hair on the last abdominal segment. 
  • Larvae have a banded appearance. 
  • Pupa — formed in the last larval skin.
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Lifecycle

  • Mating takes place outdoors after which they fly indoors to lay eggs. Normally one generation per year but development may extend to three years.

Habits

  • A common inhabitant of birds nests. Adults feed outdoors often on Spiraea plants. 
  • Larvae attack furs, skins, woollens, etc. and stored grain.

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