Stored grain insect management

Stored grain insect pests pose a serious threat to grain quality, and there is a nil tolerance for live insects at grain receival sites. Therefore, an integrated approach to insect control, including careful management of the storage environment, is critical.

When managing storage pests, prevention is always better than cure. Most problems can be overcome by effective farm hygiene, well-managed aeration cooling and correct fumigation. The following steps for storage pest management are recommended:

  • Remove grain residues from in and around empty storage and grain handling equipment before reuse.
  • Reduce introduction of insect pests to your property by thoroughly cleaning equipment and farm machinery.
  • After cleaning, consider treating storage and equipment with a structural treatment, such as an inert dust. Be aware of market requirements and withholding periods before selecting a treatment.
  • Install aeration cooling fans and an aeration controller in storages to reduce grain temperature, slow insect development and maintain grain quality. Aim for temperatures below 20oC.
  • Monitor stored grain monthly for insect pests, mould, grain temperature and grain moisture content.

Grain stored for more than six weeks should generally be fumigated for insect pests. All fumigation must be conducted in pressure-tested sealable gas-tight silos. The widespread use of phosphine has resulted in high levels of phosphine resistance in a number of stored grain insect pests. To help manage resistance, ensure that phosphine is only used when necessary and that fumigation is always conducted correctly within well-maintained gas-tight storages. Phosphine should be held at lethal concentrations for 7-10 days to ensure effective control of all insect life stages. Poor fumigation often results in a partial kill and selects for further resistance. Under phosphine label regulations, a ‘fumigation in progress’ warning sign must be displayed. A phosphine warning sign can be downloaded from the Farm Biosecurity website.

When insect pests are discovered, correct identification will allow for more targeted control options and avoid control failures due to insecticide resistance. Refer to the GRDC Stored Grain Pest Identification fact sheet for identification help. The free to subscriber SARDI insect diagnostic service is still available over summer; specimens can be posted in a non-crushable container, or images can be sent by Twitter or email (

Look out for unusual pests/diseases in stored grain, such as the khapra beetle, Trogoderma granarium, and karnal bunt, Tilletia indica, which are high priority Biosecurity threats for the Australian grains industry. Submit any unusual specimens for diagnosis, or call the Exotic Plant Pest Hotline on 1800 084 881.

More information on managing stored grain pests:

Page Last Reviewed: 22 Nov 2018
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