Common Species of Pests in Food

Appearance

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

Lifecycle

• Australian spider beetles live for up to 3 – 4 months at 20 - 25°C.

Habits

• Larvae are often found feeding on miscellaneous debris.
• Australia 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.

Appearance

• 2.0 – 3.0mm long, mottled brown in colour. 
• They have a ‘tear drop’ like body shape and are covered in short hairs. 
• Saw-tooth like antennae and elytra that do not cover the entire abdomen.

Lifecycle

• Lifecycle usually lasts 2-4 months.
• The larvae feed within the beans as they mature. 
• The larval stage can take from a few weeks to many months to complete, depending upon temperature and moisture of the bean. Pupation is within the bean. Circular holes are cut for the adult to emerge. 
• Development and breeding goes on as long as there is any food left in the bean and the temperature is right (warmer temperatures are preferred).

Habits

• Larvae feed mostly inside beans.
• These weevils attack all legumes, including kidney beans, green beans, peas and lentils. 
• Heavily infested peas are often reduced to shells.

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.

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.

Appearance

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

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.

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.

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.

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.

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

Appearance

• Adults: 3/16" in length. 
• The upper surfaces of the body are a shiny metallic bluish-green. The underside of the abdomen is dark blue. Their legs are bright reddish-brown or orange. The antennae are reddish–brown with a dark brown or black club at the tip.

Lifecycle

• Females lay up to 30 eggs per day in cracks or crevices of cured fish. The eggs take between four and six days to hatch. 
• The larvae will grow for 30 to 140 days, become less active and look for a dark place to pupate. 
• The pupal stage varies between 6 and 21 days. 
• An adult will mate soon after emerging from its pupal stage and can live for up to 14 months.

Habits

• The adults fly and can therefore easily disperse to new sources of food. 
• They are destructive in both the larval and adult stages, although the larval stage is the most destructive. 
• They are also cannibalistic, preying on their own eggs and pupae.

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.

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.

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.

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.

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.

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.

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.

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.

The Granary Weevil is among the most destructive of all stored grain insects. The larvae develop inside kernels of whole grain in storage. This makes an infestation difficult to remove in the milling process.

Appearance

• Dark brown-black in colour.
• It is about 2.5 - 5 mm in length.
• They possess a long slender snout and cannot fly.
• In the larval stage the weevils are legless, humpbacked, white to creamy white, with a small, tan head.
• Weevils in the pupa stage have snouts like the adults.

Lifecycle

• The egg, larva, and pupa stages of these weevils occur in the grain kernels and are rarely seen.
• Emergence holes of the granary weevil are fairly large and tend to be more ragged than smooth and round.
• Females drill a tiny hole in the grain kernel, deposit an egg in the cavity, then plug the hole with a gelatinous secretion.
• The life cycle is about 30 to 40 days during the summer, and 123 to 148 days during the winter, depending on temperature.

Habits

• Most of their life is spent within the grain kernel.
• Both larvae and adults feed on grain.
• Grain weevils will also attack hard cereal products, e.g. macaroni and spaghetti.

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.

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.

Appearance

• Adult — 1/4"–3/8" in length. Uppermost is black, underside is white. 
• Larva — as D. lardarius but with an orange stripe running down the length of the back.

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.

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.

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.

Merchant grain beetles are found in pantries or in food processing areas or warehouses.

Appearance

• The adult beetle is dark brown.
• Length is approximately 2.5mm to 3mm.
• It has a slender, flattened body.
• The adult can fly (although it rarely does).

Lifecycle

• The females lays about 300 eggs in her lifetime.
• Eggs are dropped loosely among grain kernels or tucked into a crevice in a kernel.
• The tiny eggs are slender and white, and hatch in three to five days when environmental conditions are optimal .
• The larvae emerge and crawl freely about the grain to feed on broken kernels. Larger larvae may tunnel into kernels to feed.
• Total development from egg to adult requires about three to four weeks.

Habits

• The Merchant Grain Beetle is a pest species found feeding in nuts, seeds, biscuits, dried fruit, grain and various other food products.
• The beetles can chew through sealed packaging such as cardboard boxes, plastic bags and foil wrappings.

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.

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.

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.

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.

Appearance

• Adult – 1/32"-1/8" long. They are shiny red-brown to black. The body is hairless, and lacks the general spider beetles characteristic restriction at the waist.

Lifecycle

• Females lay up to 120 eggs either singly or in batches during early summer. The eggs hatch within 16 days, and remain in the larval stage for up to 6 weeks. 
• Adults emerge after 20-30 days of the pupal stage and may live for up to 12 months. 
• At the optimum temperature for development (33°C) it takes about 45 days for the life cycle to be complete.

Habits

• Shiny spider beetles are tolerant of cool conditions and can stay alive for long periods without food. 
• If disturbed, they will act as if dead.

Appearance

• 1.5-4.0mm long, and oval in shape. 
• Mostly dark brown in colour, with mottled lighter brown markings.

Lifecycle

• Lifecycle usually lasts between 1.5-6 months. 
• The larva is up to 10mm long, and pale cream with indistinct dark brown markings. 
• The larva has 3 pairs of legs and is very bristly.

Habits

• This pest has recently been introduced into Australia. 
• May be found in many organic materials such as seeds, grains, most types of packaged foods, snail baits, dog biscuits, stock feeds, old rodent baits, grain remnants in sacks, bee and wasp nests, rodent carcasses, dead insects, animal droppings etc. 
• The hairs dropped by larvae may cause human problems such as asthma, skin problems or gastric disorders.

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.

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.