Don't let insects get cosy this winter

Author: Sarah Jeffrey | Date: 27 May 2014

‘Don’t give insects a cosy resort lifestyle’ is the message being delivered to grain growers this winter with a strategic storage and equipment clean out saving costly grain quality issues later in the year. 

A man cleaning up spilled seed underneath on-farm storage equipment.

Research suggests that mid-winter is a good time to do your major grain storage and equipment clean up. During the rest of the year, "clean as you go". Photo by Chris Warrick Kondinin Group.

Senior Development Agronomist with the Postharvest Grain Protection Team at Queensland’s Department of Agriculture, Fisheries and Forestry (DAFF) Philip Burrill says when it comes to controlling pests in stored grain, prevention is better than cure and winter is the ideal time to act.

“Grain residues in storages or older grain stocks held over from last season provide ideal breeding sites,” Mr Burrill said.

“Good hygiene has a significant impact on reducing storage pest numbers and winter is the ideal time to act with insects moving about much less,” he said. (See graphs.)

Recognising that growers play a pivotal role in determining grain quality for Australia’s export and domestic markets, the Plant Biosecurity Cooperative Research Centre and Grains Research and Development Corporation (GRDC) is funding insect ecology research and grain storage extension projects to provide information resources to assist growers achieve improved pest control results in on-farm storage. 

Mr Burrill’s recommendations for ensuring good stored grain hygiene include:

  • Pick a sunny day if silos need to be washed out, particularly if you had an infestation in a silo last season.  All ‘seed’ silos should be washed out and left open to dry.  DE dust (such as Dryacide) can then be applied as a structural treatment.
  • A thorough clean out of storage facilities and equipment in winter is likely to significantly reduce the spring time storage pest numbers looking to infest freshly harvested winter grains.  This, matched with good aeration cooling practice during storage, should ensure that the number of infestations and fumigation treatments required is significantly reduced. 
  • Check all monitoring and recording gear is in order and ready to use including insect sieves, probe traps, identification chart, storage record book and/or spread sheet, CVD supplies, supplies of DE, grain protectants and fumigation gear.
  • Be mindful, plan and record which storages have had insecticide structural treatments like Fenitrothion applied. Check the label with grain buyers before application. Remember that for almost all growers Dichlorvos is not able to be used on farm. See the current APVMA permit.
  • Clean grain residues from headers after the completion of sorghum harvest and apply DE. Trucks, auger hoppers, field bins, seed silos should also be cleaned out.
  • Remove grain piles from around storage facilities or any grain grading in bags in sheds. A bag of infested grain can produce more than one million insects during a year which can fly to other grain storages and start new infestations.
  • If dumping waste grain on-farm, move well away from storages and spread it out to less than 25 mm so storage pests are not provided with suitable shelter, food and a new breeding site.“Winter is also a good time for growers to check aeration equipment is in good working order and to do a pressure test on sealable silos to check for damaged rubber seals or lids,” Mr Burrill said.

Mr Burrill says being vigilant when it comes to pest control and grain quality in on-farm storage will pay dividends when it comes to marketing and confirming a grower’s long term reputation as a reliable, grain supplier.

Information on stored grain management techniques is available at the GRDC Stored Grain Information Hub at

Two handy publications are Hygiene and Structural Treatments for Grain Storage and Pressure testing sealable silos

Bar graph showing number of beetles caught per week, by month. Two variables are shown: farm storage and paddock.

This shows the number of lesser grain borers trapped each month at both "farm silo complexes" (grey bars) and numbers trapped "in paddock" (black bars) located at least 1km away from the silo complex on the same farm.  Note the very low numbers flying in winter. Also note the sudden, large flight and activity of insect in early spring. A good hygiene effort in winter should significantly reduce the storage pest numbers around harvest time that can cause an early infestation of freshly stored grain in November, December. Graph shows results from Insect Ecology project – Greg Daglish, CRC50089 of the Cooperative Research Centre for National Plant Biosecurity.

Bar graph showing number of beetles caught per week, by month. Two variables are shown: farm storage and paddock.

This documents numbers of rust-red flour beetles trapped.  They have very similar "low movement" in mid-winter however flour beetles prefer to reside around silos when compared to lesser grain borers which had large numbers flying at silos and in the paddock. Graph shows results from Insect Ecology project – Greg Daglish, CRC50089 of the Cooperative Research Centre for National Plant Biosecurity.

Contact Details 

Philip Burrill, DAFF Senior Development Agronomist
07 46603 620; 0427 696 500

GRDC Project Code PAD00001, CRC50089

Region North