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2026 GUIDE

Maize Weevil

Sitophilus zeamais

Maize Weevil is a major pest of stored grains in Australia, causing significant economic losses. It thrives in warm, humid conditions and can infest a variety of cereal grains.

Updated ·Reviewed by the LocalTradeGuide Editorial Team
Professional Treatment Recommended

For effective control and prevention, professional pest management is recommended.

Expert Identification
Control Methods
Prevention Tips

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3-5mm
Body Length
Nocturnal
Activity
Identification
Biology & Lifecycle
Habitat & Behavior
Health Risks
Control Methods
Professional Help

Maize Weevil At-A-Glance

Key facts and characteristics

3-5mm
Body Length
Negligible
Weight
Nocturnal
Activity

Complete Maize Weevil Guide

Professional identification and control information

Maize Weevil is a major pest of stored grains in Australia, causing significant economic losses. It thrives in warm, humid conditions and can infest a variety of cereal grains.

Identification

How to accurately identify Maize Weevil

Expert Tips

Look for the distinctive elongated snout and elbowed antennae for accurate identification.

Confusion Species

Can be confused with Rice Weevil; distinguished by longer snout and larger size.

Key Identification Features

Reddish-brown color, elongated snout, and elbowed antennae are key features.

Biology & Lifecycle

Understanding Maize Weevil biology and development

Anatomy

Maize Weevil have a distinctive elongated snout and elbowed antennae, adapted for grain feeding.

Genetics

Population genetics show adaptation to stored grain environments in Australia.

Lifecycle Details

Egg Stage

Eggs are laid inside grains and hatch in 5-7 days.

Adult Stage

Adults live for 2-3 months, feeding and reproducing.

Pupal Stage

Not applicable; larvae develop inside grains.

Larval Stage

Larvae develop inside grains, feeding on the endosperm.

Development Time

4-8 weeks.

Reproduction Rate

Multiple generations per year under favorable conditions.

Habitat & Distribution

Where Maize Weevil lives and thrives

Hiding Spots

  • Inside stored grains
  • Grain storage facilities
  • Sacks and containers

Nesting Behavior

Lays eggs inside grains, larvae develop within.

Preferred Habitats

  • Stored grain facilities
  • Grain silos
  • Warehouses

Humidity Preference

Prefers high humidity environments.

Nesting Requirements

Requires intact grains for egg-laying and larval development.

Temperature Preference

Thrives in warm, humid conditions typical of Australian summers.

Distribution Patterns

Native Range

Native to tropical regions but widespread globally.

Climate Zones

Found in tropical and subtropical zones of Australia.

Urban Vs Rural

Common in both urban storage facilities and rural grain silos.

Introduced Range

Widespread across Australia.

Spread Mechanism

Spread through grain movement and storage facilities.

Australian States

Present in all Australian states and territories.

Establishment Factors

Thrives in warm, humid conditions and abundant grain storage.

Behavior & Diet

Maize Weevil behavioral patterns and feeding habits

Social Behavior

Solitary but can aggregate in large numbers in stored grains.

Activity Pattern

Nocturnal, active during cooler periods.

Foraging Behavior

Larvae feed inside grains, adults feed on grain surfaces.

Dispersal Behavior

Disperses through flying and grain movement.

Territorial Behavior

Not territorial; aggregates in infested grains.

Dietary Preferences

Aphid Farming

Not applicable.

Feeding Habits

Feeds exclusively on stored grains, particularly maize.

Foraging Range

Limited to stored grain environments.

Feeding Patterns

Larvae develop inside grains, while adults feed on grain surfaces.

Primary Food Sources

  • Maize
  • Wheat
  • Rice

Seasonal Diet Changes

No significant seasonal changes.

Health Risks

Health concerns associated with Maize Weevil

Important Health Information

Always consult healthcare professionals for medical concerns related to pest exposure.

Allergens

None known.

Contamination Risk

High risk of grain contamination.

Disease Transmission

Not a known vector.

Economic Impact

Financial costs and economic effects of Maize Weevil

Grain Losses

A single tonne of infested grain can produce more than one million insects during a year, and because adult maize weevils are strong fliers they can walk and fly to other grain storages to start new infestations on neighbouring farms.

Field research in the Condamine region and Central Queensland found that storage pests such as the maize weevil could fly 1–2 km to find grain to infest, so even a farm with good hygiene should be alert to incoming pests.

Straight out of the paddock, Australian wheat and barley typically go into storage at 30–35°C — temperatures known to be ideal for rapid breeding of the maize weevil and other key storage pests — so without fast aeration cooling, pest numbers and associated grain damage escalate quickly. Unmanaged infestations then add fumigation and re-conditioning costs before affected grain can be sold.

Market Access And Quality

Insect contamination and live infestation can lead to downgrades and delivery rejection at Australian receival points, threatening the reputation of Australian grain in export markets, so protecting Australia's grain markets requires planning for insect control before grain is stored.

The maize weevil (Sitophilus zeamais) is a strong flier and very similar in appearance to the rice weevil (Sitophilus oryzae), so correct identification matters for selecting effective treatments and meeting quarantine requirements.

Detection & Signs

Early warning signs of Maize Weevil presence

Trapping And Probes

Probe traps pushed into the grain surface can detect the start of an infestation when regularly monitored: place 1–2 traps in the top of a silo, or several traps in grain stored in sheds, and pull them up for inspection fortnightly or monthly.

Sieving And Sampling

Damage by grain insect pests often goes unnoticed until the grain is removed from storage, so the first detection step is sieving samples through a 2 mm mesh onto a white tray, then holding the tray in sunlight for 10–20 seconds to trigger movement of any insects. Sitophilus zeamais, described by Motschulsky in 1855, is confirmed as an established Australian species by the Australian Faunal Directory.

Sampling results from farm silos show that if 600 adult beetles are sieved from a tonne of grain, close to 60,000 eggs, larvae and pupae may be present yet invisible, because the white larvae feed and develop inside the grain kernels.

Monitoring Frequency

Sample each grain storage at least monthly, with fortnightly sampling recommended during warmer periods of the year, taking samples from the top and bottom of the grain store, and check grain three weeks prior to sale to allow time for fumigation if required.

Prevention

Proactive strategies to prevent Maize Weevil infestations

Record Keeping

Making full use of good hygiene and aeration cooling can overcome up to 70% of pest problems, alongside identifying pest incursions early through regular monitoring.

Clearly number each silo and keep up-to-date storage records of where each variety and grain quality segregation is stored, and record any grain treatments for the commodity vendor declaration (CVD).

Aeration Cooling

Aeration cooling in Australian storages should achieve 18–23°C during summer months and under 15°C in winter, monitored each month with a grain temperature probe, with fans run as soon as the first few truckloads go into storage at harvest time.

Straight out of the paddock, Australian wheat and barley typically enter storage at 30–35°C, which is ideal for rapid breeding of storage pests, so unless grain temperatures are reduced quickly using aeration cooling, pest numbers will increase rapidly along with associated grain damage.

Hygiene Practices

Grain residues provide shelter and food for pests and allow large numbers to build up and infest other grain storage sites under favourable conditions such as the start of spring, so all grain residues should be removed to limit the areas where insects can survive and breed.

Apart from bulk stored grain, pests can breed in small grain residues present in headers and other farm machinery and infest newly harvested grain, and grain spillages around storages may also provide infestation sites.

Control Methods

Effective treatment options for Maize Weevil control

Fumigation Practices

When fumigating stored grain, always read the chemical label and follow all directions, as fumigants such as phosphine are only effective when used in gas-tight, sealable grain storage facilities.

Repeated overuse or reliance on chemical controls often leads to development of pesticide resistance, so aeration cooling and hygiene should be applied first to reduce reliance on repeated phosphine fumigation.

Integrated Management

An integrated approach to pest control is crucial for growers increasing the amount of grain stored on farm, with four key factors in stored grain protection: hygiene, aeration cooling, regular pest monitoring and recording, and correct fumigation practices.

By using a combination of non-chemical and chemical control measures, growers minimise storage pest numbers, grain losses and the costs they add to grain sales, while extending the useful life span of grain protectant and fumigation products.

Professional Services

Featured Stored-product-insects Control Providers

Connect with verified, professional pest control specialists in your area. These providers are highly rated and experienced in stored-product-insects control.

Seasonal Patterns

Maize Weevil seasonal activity and management timing

Autumn

Activity decreases in cooler autumn months in Australia.

Frequently Asked Questions

Common questions about Maize Weevil

Are Maize Weevil dangerous?

Maize Weevil are not dangerous to humans but cause significant economic losses to stored grains.

How do I identify Maize Weevil?

Identify by their reddish-brown color, elongated snout, and elbowed antennae.

How do I control Maize Weevil?

Control through proper grain storage, fumigation, and use of insecticides.

Get Expert Help with Maize Weevil Control

Need professional assistance with Maize Weevil identification or control? Our network of certified pest control experts can provide tailored solutions for your specific situation.

Why Choose Professional Help?

  • Accurate Maize Weevil identification
  • Safe and effective treatment methods
  • Customized control strategies
  • Experienced pest control technicians
  • Ongoing prevention advice

Emergency Response

Some providers offer emergency callouts for urgent stored-product-insects issues — check availability

Expert Consultation

Free quotes and professional assessment

Experienced Help

Professionals experienced in treating this species

Other Stored-product-insects Species in Australia

Almond MothAngoumois Grain MothBean WeevilBookliceBooklouse (Psocid)Cheese Mite

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