STORED GRAIN PESTS IDENTIFICATION
Lesser Grain Borer
Can the insect walk up the side of a glass jar β NO β Are the insects cylindrical dark brown β Yes! Lesser Grain Borer.
This borer is a major pest as it develops resistance to grain insecticides.
FEATURES: The overall shape of the body is slim and cylindrical, It is a dark brown beetle (up to 3mm long) and has club-like antennaeβs. They are strong flyers, and their mouth parts and eyes are tucked underneath the thorax (chest)
LIFE CYCLE: At 35Β°C they complete their life cycle within 4 weeks (28 days). At 22Β°C they complete their life cycle within 7 weeks (49 days). Breeding does not continue below 18Β°C and females lay between 200 β 400 eggs on grain surfaces. Young larvae has white and brown heads and feeds outside before they bore into the grain
Adults live for 2 β 3 months.
DETECTION: Their habit is to remain hidden in grains and can only be detected with regular siftings.
Rust-Red Flour Beetle
Can the insect walk up the side of a glass jar β NO β Are the insects Flattish red-brown and longer than 3mm with short antennaeβs β Yes, then Rust-red flour beetle
Rust-red flour beetles are found in stored cerealβs, processed grain products, oilseeds, nuts and dried fruit.
KEY FEATURES: Adult beetles (3 β 4.5mm long) is bright reddish-brown in colour when younger and a darker brown when older. At the end of their antennae, you can find three larger segments.
Similar species: Tribolium confusum that is also known as the confused flour beetle and mostly common in cooler temperature regions.
LIFE CYCLE: At 30Β°C they complete their life cycle within 4 weeks (28 days). At 22Β°C they complete their life cycle within 11 week (77 days). Reproduction does not continue below 20Β°C and adults live from 200 days to 2 years. Beetles moves quickly, fly in warmer conditions and the female that can give up to 1000 eggs, scatters their eggs loosely throughout the commodity
The larvae is a cream color and feeds externally on damaged grains and the beetles infest whole grains. Breeding is more successful on dried stored products like flour.
DETECTION: Use a strainer or a probe trap to detect the beetle.
They preferred to be around storage areas with poor hygiene, broken grain, gradings or bulk cottonseed.
Rice Weevil
Can the insect walk up the side of a glass jar β Yes β Do the insect have a snout β Yes β then Rice Weevil?
Mostly feed on whole cereal grains and a major pest.
KEY FEATURES: The most common feature of this beetles is the βsnoutβ. Adults are dark brownish black in colour (2 β 4mm long), and their rear wings covers have 4 small light-colored patches but rarely flies.
Similar species: Sitophilus zeamais β maize weevil & Sitophilus granarius β granary weevil.
LIFE CYCLE: Adults have a livespan of 2-3 months. Larvae generally feeds inside single grains, and you would not see them.
At 30Β°C they complete their life cycle within 4 weeks (28 days). At 18Β°C they complete their life cycle within 15 week (105 days). Reproduction does not continue below 15Β°C
DETECTION: Rice Weevils are often observed in warmer conditions when you move the grains and they climb out of the grain up vertical surfaces.
Flat Grain Beetle
Can the insect walk up the side of a glass jar β NO β Are the insects Flattish red-brown and Ant-like & are they less than 3mm long with long antennaeβs β Yes β then flat grain beetle
They normally feed on damaged grain and infests most stored grain products. They also have a high level of resistance to phosphine.
KEY FEATURES: They are very flat and smaller than other stored grain pests (2mm long), with long thin antennae and reddish brown in colour.
Adult can fly and is fast moving when seeking cover under trash or grains.
The most common species is the C. ferrugineus and the Cryptolestes species with the same appearance.
LIFE CYCLE: At 30 β 35Β°C they complete their life cycle within 4 weeks (28 days). with moist conditions, 13 weeks At 20Β°C with moist conditions they complete their life cycle in 13 weeks (91 days). Reproduction does not continue below 17.5Β°C
Larvae have tails and horns and feed / develop on damaged grains externally
300 eggs get laid by females loosely in the grain stack.
DETECTION: Use a strainer or a probe trap to detect and if the treatment failed need to send a insect sample for testing as they are resistant to phosphine.
Saw-Toothed Grain Beetle
Can the insect walk up the side of a glass jar β Yes β Do the insect have a βsnoutβ β No β then Saw-toothed Grain Beetle?
Mostly infesting and feeding on cereal grains, oilseeds, processed products, peanuts and dried fruits.
KEY FEATURES: The adults are a dark brown-black beetle (up to 3mm long), fast moving and fly in warmer temperatures. They can also climb vertical surfaces
The beetleβs thorax (chest) has 3 ridge lines on top and zigzag patterns on each side
LIFE CYCLE: Prefers damaged or processed grain. Adults can live for several months, and the females loosely lay 300 β 400 eggs, throughout the grain. The white larvae always feed and develop externally
Life cycle completed in 3 weeks at 30 β 33Β°C they complete their life cycle in 3 weeks (21 days) and at 20Β°C they complete their life cycle in 17 weeks (119 days). Reproduction does not continue below 17.5Β°C.
DETECTION: Use a strainer or probe traps to detect. These beetles have already developed a resistance to a number of grain insecticides.
Pscoids β Booklice
A wide range of grains, products and storage facilities can be infested with Pscoids
KEY FEATURES: Very small insect with a soft cloudy body that is pale in colour (up to 1mm long). They are secondary pestβs that feeds on damaged grains and molds and often appear as a βmoving carpet of dustβ
They are a mixed populations with 3 main species.
LIFE CYCLE: Life cycle is 21 days in warm (25Β°C) and moist conditions (75% relative humidity).
To get to adult stage the eggs are laid on grain surfaces then hatching to nymphs that molt through to an adult.
DETECTION: Activity increases with warm and humid conditions, and you can find them in storage or on grain surfaces. Sample and filter to detect these beetles.
BRUCHIDS: Cowpea weevils
Most pulse crops, including mung beans, cowpeas, field peas, chickpeas, soybeans, and lentils gets infested by these Callosobruchus
KEY FEATURES: Adults has spherical, tear-shapes bodies and is reddish brown with black and grey markings (up to 4mm long). Adults emerge through round holes in seedβs and can climb vertical surfaces.
Wing covers (elytra) do not fully cover the abdomen but are still strong Flyers with long antennae.
LIFE CYCLE: Adult have a short lifespan of only 10 β12 days and donβt feed but lay 100 white eggs on the outside of seed. Adults also lay eggs on mature seed pods in a standing crop unlike most stored pests.
Larvae feed and develop within seeds and leaves a round hole when they emerge as adults.
DETECTION: In warmer months a problem can occur for mung beans.
To prevent serious losses, fortnightly sampling and sifting is needed.
Pea Weevil
Can the insect walk up the side of a glass jar β Yes β Do the insect have a snout β Yes β then Weevil?
In Western Australia these pests can cause a lot of damage to field peas, but they also appear in storage after they emerged.
KEY FEATURES: Adult have ball-shaped bodies with a length of 4 β 5mm, with long legs and antennae. Adults are strong flyers with patterned wings with white / cream spots.
Before harvesting, they lay and glue eggs onto pods in standing pea crops. Adult emerges through a neat round hole in the seed and reappear in spring to visit flowers to feed on the nectar then seek out new field peas crops to lay eggs.
LIFE CYCLE: Larvae grow and pupate after they bore through the seed pod and into a single seed where they feed. Adults lives long and hibernate leaving them breeding only 1 generation per year.
DETECTION: Adults shelter in nearby trees under the bark and migrate into crops from seed sources. When there is a neat round hole in the pea seedβs it is evidence of adults that have emerged.
When the first pods are forming and when the temperatures are above 18Β°C, field peas should be regularly checked with a sweep net, in and around the crop edges.
MOTHS
Angoumois Grain Moth
These pests only infest surface layers of bulk-stored grains like cereal. It is common to see infestations of standing maize crops before harvesting. Occasionally in other cereal crops as well.
KEY FEATURES: Adults is 5 β 7mm long, their wings have a long border of fine hair along the back edge and is silvery grey to grey, brown that narrows to a point.
Adults only infest surface layers of bulk grain as they cannot penetrate the grains.
LIFE CYCLE: These moths do not create webbing and do not feed. As they canβt penetrate grainβs they lay 150 β 300 eggs on or near the grain surfaces.
Larvae burrows into a single grain and feeds and develops into an adult that emerges in 10 β 14 days through a visible hole. In warmer conditions the life cycle takes 5-7 weeks.
DETECTION: When doing monthly samples, look for moths near grain surfaces or even pupal cases that gets left behind by the adults that they emerged out of.
Indian Meal Moth
These pests infest the surface of all types of grains including flour mills, processing plants, dried fruit.
KEY FEATURES: Adults can reach 5 β 7mm in length with wings that is dark reddish brown on the back half of the wing and grey at the front leaving the wings bicolored.
LIFE CYCLE: Female month lay 200 β 400 eggs on raw material of food and in summer the life cycle takes about 4 weeks.
When the larvae feed, they create webbing and then cocooned several grains webbed together in a group
DETECTION: When taking monthly samples, you need to look for webbing, residues on grain harvesting and handling equipment and moths near grain surfaces.
Warehouse Moths
These pests infest flour mills, food processing plants, cereal grains, and oil seeds.
KEY FEATURES: Adult moth body length is 8 β 10mm, has grey wings with fine, dark wavy markings, it also has lighter stripes on each forewing going across horizontally.
On the grain surfaces you will see webbing created by larvae.
LIFE CYCLE: Adult moths do not feed and are short-lived with a life cycle completed in 30 days with weather at 30Β°C and 75% relative humidity. Female lays between 100 β 270 eggs on or near grains over a two-week period.
Caterpillars are light pink in colour and at the base of each hair it has a small black spot.
DETECTION: Samples should be done on a monthly basis, and you would be able to spot moths and / or webbing near grain surface. Most activity is during dusk and dawn.
