STORED PRODUCT INSECT SPECIES

Common Stored Product Insect Species

Stored product insects (SPI) damage foodstuff and raw materials and contaminate finished products, hence making them unfit for use. Understanding the appearance, habits and life cycles of SPIs can help identify the most effective SPI control for your property.

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Lesser Grain Borer

(Rhyzopertha Dominica)

lesser grain beetle

Appearance

  • The adult is 2–3 mm in length.
  • Ranges from red-brown to black-brown.

Lifecycle

  • Female produces 200–500 eggs.
  • At an ideal temperature of 34°C and 70% Relative Humidity (RH), pupation takes up to 3 days.
  • At ideal temperature (34°C and 70% RH), the life cycle lasts around 3—4 weeks.

Habits

  • Eggs are laid in crevices or on the rough surfaces of a seed.
  • The larva will bore inside the grain to continue growing.
  • The larva develops faster on whole-grain compared to flour.
  • Adult mate as soon as they emerge.
  • Commonly found in warehouse and store.

Drugstore Beetle/Biscuit Beetle

(Stegobium panicum)

Drugstore Beetle- Biscuit beetle

Appearance

  • The adult is 2–3.5 mm in length.
  • Light brown in colour and oval in shape.
  • Antennas end with a 3–segmented club.

Lifecycle

  • Female produces 20–100 eggs.
  • Eggs take around 60–210 days to develop into adults, with 1–4 generations per year depending on the temperature.
  • Adult lives for about 13–65 days

Habits

  • Adults are active fliers, especially during the afternoon to evening time.
  • Commonly found infesting processed goods such as chocolate, confectionery and biscuits. Also often found on dried food product such as dried herbs and spices.

Cigarette Beetle

(Lasioderma serricorne)

cigarette beetle

Appearance

  • The adult is 2–3 mm in length.
  • Light brown to reddish-brown.
  • Antennas are about half of their body length and are shaped serrated (saw-like).

Lifecycle

  • Female produces up to 30–42 eggs.
  • Eggs take 30–90 days to develop, with 3–6 overlapping generations per year.
  • Adult lives 23–28 days.

Habits

  • The larva produces a cell of food fragments and waste materials to pupate.
  • Adults are active fliers, especially during the afternoon to evening time.
  • The adult does not feed while the larva is the one doing the damage.
  • Feeds off tobacco, dry stored food products, spices, seeds, grains and dried plant material.

Rusty Grain Beetle

(Cryptolestes ferrugineus)

rusty grain beetle

Appearance

  • The adult is 1.5 – 2.5 mm in length.
  • Red-brown in colour with a flat body.

Lifecycle

  • Female produces up to 200 eggs.
  • In ideal temperature conditions, the life cycle is about 23 days.

Habits

  • Adults walk with a characteristic swaying movement.
  • Adults are winged but rarely fly.
  • Feeds on cereals, dates, dried fruits and other materials.

Saw Toothed Grain Beetle

(Oryzaephilus surinamensis)

saw toothed grain beetle

Appearance

  • The adult is about 2.5–3 mm in length.
  • Six sawlike teeth on each side of the prothorax

Life Cycle

  • Female produces 45–285 eggs.
  • The life cycle takes about 30–50 days.

Feeding Habits

  • Larvae feed within mass produce.
  • Adults are winged but do not fly.
  • Often wander from food into cracks, crevices and roof spaces to hide.

Khapra Beetle

(Trogoderma granarium)

khapra beetle

Appearance

  • The adult is 2 – 3 mm in length.
  • Dark brown with the light brown pattern on wing covers.
  • Oval in shape.

Lifecycle

  • Female can lay up to 35 eggs.
  • It takes about a month to complete the life cycle.

Habits

  • Larvae make the most damage on stored products by shedding cast skin and feeding on materials.
  • It can survive up to 9 months without food.
  • Commonly found infesting grains, cereals and pulses.

Copra beetle/Red-Legged Ham Beetle

(Necrobia rufipes)

copra beetle

Appearance

  • The adult is around 3.5–7 mm in length.
  • Shiny green to bluish-green with red legs.

Lifecycle

  • Female lays up to 30 eggs per day in cracks or crevices of cured fish.
  • Adult lives up to 14 months.

Habits

  • It commonly feeds on dried copra and other insects that are attracted to mouldy food.
  • Infest areas such as palm kernels, oilseeds, spices, dried fish and other meat products.
  • Adults are slow fliers and will bite human when disturbed.

Granary Weevil

(Sitophilus granarius)

granary weevil

Appearance

  • The adult is 3–4.8 mm in length.
  • Reddish-brown to black.

Lifecycle

  • Female lays eggs in grain kernel cavity.
  • At ideal temperature conditions (30°C), it takes 30 days to complete the life cycle.

Habits

  • Newly emerged adult leaves large ragged holes.
  • Feeds on grains and complex cereal products such as macaroni and spaghetti.

Rice Weevil

(Sitophilus oryzae)

rice weevil

Appearance

  • The adult is 2.5–3.5 mm in length.
  • Brown to black with reddish spots on the back of the abdomen.
  • Has a long slender snout.

Lifecycle

  • Female lays 300–400 eggs.
  • It takes as short as 32 days to complete the life cycle.
  • Adult lives up to 3–6 months.

Habits

  • Female drills a tiny hole in the grain kernel to lay an egg in the cavity.
  • Grows feeds and pupates within a grain kernel.

Flour Beetle

(Tribolium castaneum)

flour beetle

Appearance

  • The adult is 3–4 mm in length.
  • Reddish-brown in colour.

Lifecycle

  • Under optimal conditions, it takes 20 days to develop from egg to adult.

Habits

  • Larva and adult feed on various durable commodities such as groundnuts, nuts, spices, coffee, cereals, dried fruits and animal feed.
  • Disperses by flying and does not depend on humans’ movement of food products.