Chemical control of buffalo fly

Chemical treatments help manage high buffalo fly numbers and provide immediate relief.

When you combine chemical treatments with non-chemical methods, you improve long-term buffalo fly control and slow the development of insecticide resistance.

Use chemical and non-chemical methods

Chemical treatments should be used only when fly pressure is high, and non-chemical methods should be used to reduce breeding and keep fly pressure lower over time.

This integrated approach helps you:

  • reduce reliance on repeat treatments
  • slow the development of insecticide resistance
  • maintain effective control year after year.

Chemical treatments work best when you use them when they are needed, not as a routine.

Industry guidance thresholds:

  • beef cattle—200 flies per animal
  • dairy cattle—30 flies per animal

Use a consistent counting method to compare results over time and avoid unnecessary repeat treatments.

Insecticide resistance

Buffalo flies have a short life cycle, so they can develop resistance to insecticides quickly.

Resistance does not always mean chemicals stop working completely. It can mean the protection period is shorter than expected, or shorter than the label claims.

To slow resistance:

  • Rotate chemical groups where practical rather than relying on the same group season after season.
  • Follow label directions and do not use a product beyond the label's instructions. Remove or stop use as directed.
  • Dose correctly every time (both underdosing and overdosing reduce control and may accelerate resistance).
  • Keep treatment records to plan rotations and avoid accidental overuse.
  • Use an integrated approach. Combine chemical treatments with manure management, biological control and other long-term methods.

Also consider rotating chemical groups across tick, lice, and mite treatments to avoid overusing the same chemical group.

Use chemicals safely by following the label directions and safety warnings, including wearing personal protective equipment (PPE).

Check the Australian Pesticides and Veterinary Medicines Authority (APVMA) before you choose a product or rotate chemical groups.

Know the active ingredient (not just the brand)

Every product contains an active ingredient (the chemical that does the work). Products with different brand names may use the same active ingredient or actives from the same chemical group.

Actives in the same chemical group often work in similar ways. Resistance to 1 active can lead to cross-resistance to other actives in the same group.

Product packaging doesn't always indicate the chemical group. Check the active ingredient on the label to identify the group when planning rotations. Use the ParaBoss Product Search tool to help.

Understand WHP and ESI

Product labels show withholding periods and export slaughter intervals.

  • Withholding period (WHP) is the minimum time you must wait between treating cattle and using their meat or milk for human consumption.
  • Export slaughter interval (ESI) is the minimum time you must wait between treating cattle and slaughter for export markets.

Always follow the label WHP and ESI for the product you use. This helps prevent chemical residues in meat or milk and protects your market access (including export eligibility).

Chemical groups

Isoxazolines (ISZ)

Isoxazolines are insecticides that disrupt an insect's nervous system, targeting flies, ticks and mites.

ISZs:

  • provide effective and long-lasting control of buffalo flies
  • have no detected resistance in buffalo flies
  • require correct application across all cattle for effective control
  • also affect other external parasites, such as ticks and mites (use them when they suit the parasites you need to treat).

Organophosphates (OP)

Organophosphates are synthetic insecticides that disrupt an insect's nervous system, targeting flies, ticks and lice.

OPs:

  • kill insects within 4–8 hours
  • are toxic to humans (use PPE as directed and handle, store, and dispose of carefully)
  • require correct application across all cattle for effective control
  • can develop resistance in buffalo fly populations, so rotate chemical groups where practical.

Synthetic pyrethroids (SP)

Synthetic pyrethroids are insecticides that kill insects quickly by causing paralysis, targeting flies, ticks and lice.

SPs:

  • may repel other flies
  • are generally low-risk to people but can irritate skin and eyes
  • require correct application across all cattle for effective control
  • face widespread resistance in buffalo flies (avoid relying on SPs alone season after season).

Macrocyclic lactones (ML)

Macrocyclic lactones are insecticides made from natural compounds produced by soil microorganisms, targeting flies, ticks, lice, mites and roundworms.

MLs:

  • kill insects quickly
  • have no detected resistance in buffalo flies
  • require correct application across all cattle for effective control
  • also affect other parasites, including worms (use them when they suit the parasites you need to treat).

Treatment methods

Different methods suit different times of year, labour availability, and cattle-handling systems. No single method works best in every situation.

Ear tags (SP, OP, ML)

Ear tags are plastic tags that release insecticide slowly over time. Cattle then spread the insecticide over their bodies as they swat flies.

For buffalo fly control:

  • use tags when fly worry is obvious or when numbers exceed industry thresholds
  • tags can remain effective for up to 16 weeks
  • rotate tag groups to reduce resistance pressure (for example, Year 1 SP, Year 2 OP, Year 3 ML)
  • remove tags once the product has expired. If you still need protection, switch to a different method and chemical group.

Remove tags before slaughter or export as required. Most products have no WHP or ESI, except abamectin tags, which have a 42-day ESI.

Ear tags generally pose no major threat to dung beetles.

Pour-ons (SP, ML, ISZ)

Pour-ons are insecticides you apply along the backline. They are fast and easy to apply, but accurate dosing is essential.

For buffalo fly control:

  • weigh cattle and calibrate equipment to avoid underdosing, which is common
  • treat all cattle to reduce uneven coverage from social licking
  • repeat treatments may be needed
  • check WHP and ESI requirements.

Some pour-ons can be toxic to dung beetles.

Sprays (SP, OP)

Sprays are insecticides you apply to the coat by hand-spraying or spray races. They provide rapid knockdown and short-term relief.

For buffalo fly control:

  • follow label directions for dilution and apply thoroughly (control depends on coverage)
  • plan for frequent re-application if fly pressure remains high
  • use PPE and handle chemicals safely
  • check WHP and ESI requirements.

Dips (SP, OP)

Dips are insecticide baths that wet cattle completely and kill flies on contact. They provide immediate relief but require infrastructure and strong chemical management.

For buffalo fly control:

  • wet cattle fully, including the head and ears
  • maintain the correct chemical concentration
  • reduce chemical exposure risk through training and PPE
  • follow WHP and ESI requirements.

Backrubbers (OP)

Backrubbers are chains wrapped in burlap soaked with oil and insecticide. Cattle apply the insecticide to themselves by rubbing against the backrubber.

For buffalo fly control:

  • position backrubbers in high-traffic areas (such as walkways to water or feed), or if needed, in shade or common resting areas
  • monitor use and move the backrubber if cattle are not using it
  • do not leave backrubbers in place when fly numbers are low, as this can increase resistance
  • if you use other methods in the same year, choose non-OP options to reduce the risk of resistance
  • check WHP and ESI requirements.

Restrict backrubber use for lactating dairy cattle.

Record-keeping

Record:

  • what you used (product, active ingredient, chemical group and method)
  • when you treated
  • how well it worked.

Use those records to plan your next rotation, avoid using the same chemical group for too long and reduce unnecessary re-treatment.

More information