Stored Grain Management: Stored Grain Insects

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Stored Grain Management: Stored Grain Insects

Author:	OMAFRA Staff
Creation Date:	01 March 2002
Last Reviewed:	27 September 2005

Agronomy Guide > Pub 811: Stored Grain Management > Stored Grain Insects

Excerpt from Agronomy Guide for Field Crops (Chapter 10)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Scouting Technique for Stored Grain Insects
Insect Management Strategies for Farm-Stored Grain - Table 10-2
Updates on Stored Grain Management: Stored Grain Insects Identification
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Scouting Technique for Stored Grain Insects

In the grain pile, place four plastic probe traps halfway between the centre and edge of the bin, in an X pattern, with the centre of the bin as the centre point of the X. Place the traps about 5 cm (2 in.) below the grain surface. Retrieve and examine them at least once a month. These probe traps are very sensitive and will show an infestation well before it is economically threatening.

Plate 148. Insect probe for stored grain is inserted into grain to trap insects.

If insects are present in probes, follow the management strategies listed in Table 10-2. Insect Management Strategies for Farm-Stored Grain.

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Table 10-2. Insect Management Strategies for Farm-Stored Grain

Rusty Grain Beetle

Plate 149. Rusty grain beetle adults have antennae as long or longer than their head and thorax combined.

Rusty grain beetle
Description	flat, reddish-brown beetle approx. 2 mm (1/16 in.) long antennae are as long or longer than its head and thorax combined flies when temperatures are above 25°C (77°F) Larvae are white, approx. 3mm (1/8 in.) long, have two brown projections at the rear moves easily through the whole grain pile because of its small size
Life History	cold-tolerant overwinters as an adult lays up to 500 eggs on surface of kernels larvae hatch in 3-5 days larvae penetrate seed and pupate inside adults emerge, leaving distinctive exit hole
Damage	adult and larvae feed on germ and bran feeds on cracked or sound grain feeds throughout pile of grain high infestations generate heat, causing grain to mould and spoil
Management Strategies	proper sanitation and monitoring practices use treatment with diatomaceous earth to protect from re-infestation refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information

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Indian Meal Moth

Plate 150. Indian meal moths leave webbing on the top of the grain pile.

Indian Meal Moth
Description	adult approx. 12 mm (1/2in.) long "A-shaped" when wings are at rest wings are grey, bottom half are bronzy active in the evening larvae grow to approx. 8mm (3/8in.) long larvae range from pinkish-cream to pale yellow to pale green/yellow with black heads larvae have three pairs of legs on thorax, five pairs of abdominal prolegs mature larvae wander, looking for places to pupate
Life History	can go through its entire life cycle in approximately 21-30 days under warm conditions not cold-tolerant temperature limits number of generations per year females lay eggs on kernels of grain on pile surface young larvae found in grain clumps (3-10 kernels) held together by silk
Damage	adults do not feed or cause damage larvae feed on germ and bran, leaving kernels with these missing all stages of larvae spin webbing (increases as preparing to pupate) typically stays on top of pile, no more than 50 cm (20 in.) deep high populations result in a mat of grain with silks up to 50 cm (20 in.) deep
Management Strategies	moth is resistant to malathion remove webbed layer of grain before fumigation refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information

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Granary Weevil

Plate 151. Granary weevil is a snout beetle that has oval pits on the surface of the thorax.

Granary Weevil
Description	adult is a dark brown snout beetle approx. 4 mm ( 3/16 in.) long larvae are white, wrinkled and wingless, 4 mm (3/16 in.) long larvae always found inside grain, only leave kernel as adults only attacks cereal grains, not legumes cannot fly can be confused with rice weevil on surface of thorax, the small pits are round rather than oval, cannot survive cold
Life History	female lays eggs into holes in the grain created with her snout cements holes shut larvae develop inside grain adults live up to 8 months
Damage	adult and larvae feed on sound grain larvae spend entire life in one kernel, feeding on endosperm several larvae can be inside one kernel leaves round exit holes when exits kernel as adult
Management Strategies	refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information

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Pea/Bean Weevils
Description	two species that attack peas or beans damage and larvae resemble that of granary weevil adults are short and squat (3-4 mm or 1/8 - 3/16 in.) heads are tapered at front usually tan coloured with faint longitudinal striping larvae are creamy yellow coloured, legless, and have a brass-coloured head capsule
Life History
Damage	pea weevils attack peas, bean weevils attack beans adults lay eggs in maturing beans in field with no apparent visible damage damage noticed when new adults emerge from seeds, leaving round holes
Management Strategies	monitor beans for damage in storage react with a fumigation sort beans visually to remove "picks" heavily infested peas or beans can be fed to livestock refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information

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Lesser Grain Borer

Plate 152. Lesser grain borer's head is turned downward and covered by a large hood (prothorax). A must odour is often associated with this pest.

Lesser Grain Borer
Description	adult is a brown-to-black beetle approximately 2 mm (1/16in.) long cylindrical in shape small numerous pits on surface of wings adult identified by location of head head is turned downward and covered by large hood (prothorax) larvae are creamy-white, C-shaped, with a dark head tucked into the thorax musty odour associated with this pest
Life History	female borer lays eggs in cluster on surface of kernels larvae hatches and bores into the kernel completes development inside kernel
Damage	pest may move into Ontario due to climate warming adult and larvae cause damage to sound grain bore irregularly shaped holes into the grain leave only shell and powdery dust adult and larvae enter and exit several grain kernels several individuals may attack same kernel also feed off grain dust
Management Strategies	advise provincial field crop entomologist if found refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information

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Grain Lice
Description	also known as psocids or book lice adults are soft bodied approximately 1-2 mm (1/32 - 1/16 in.) long have large heads with long antennae range from brown to white and often are opaque can be winged or wingless resemble aphids young are smaller and slightly paler than adults
Life History	incomplete metamorphosis (young nymphs resemble adults) several generations can multiply quickly under warm conditions
Damage	not a direct pest of grain secondary pest that feeds on grain dust and damaged kernels can be seen running over pile when numerous visually inspect grain surface for tiny, fast-moving insects generally restricted to the top of the grain pile
Management Strategies	turning and cleaning the grain reduces populations lice are found in damp conditions lowering humidity lowers populations refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information (Order OMAFRA Publication 812)

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Mites
Description	adults barely visible to the naked eye approx. 0.5 mm ( 1/64 in.) long rounded eight-legged yellowish-brown larvae look like adults but have six legs two nymphal stages look similar to adult with four pairs of legs
Life History
Damage	incidental insect on grain going out of condition prefers damp grain feeds on grain dusts and moulds
Management Strategies	keep grain dry and in good condition refer to OMAFRA Publication 812, Field Crop Protection Guide, for insecticide and fumigant information (Order OMAFRA Publication 812)

Updates on Stored Grain Management: Stored Grain Insects

Stored Grain: European Grain Moth

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