Insecticidal Ear Tags

• Most widely used for buffalo fly control, but they can also affect other external parasites. Some tags also have claims for activity against some types of lice and for the control of paralysis ticks.
• Delay applying ear tags until fly worry is obvious or until beef cattle are carrying more than 200 flies each.
• Application of insecticidal tags should be timed to protect cattle through the main fly period on your property.
• Use a synthetic pyrethroid (SP) one year, an organophosphate (OP) tag the next year and an abamectin (ML) tag in the third year.
• Remove tags once the protection period on the label has expired to avoid exposing flies to sub-lethal concentrations of the chemical, which increases selection for resistance.
• If fly protection is required early in the season, or after the tags have expired, use a spray or pour-on product from a different chemical group.

Resistance

A parasite population can develop resistance to a chemical through:

• Repeated use of the same active.
• Repeated overuse of a chemical (unnecessary treatments).
• Wide-spread under-dosing of a chemical (e.g. under-estimating the weight of the animals being treated, poor application technique, uncalibrated dosing equipment).
• Unintentionally exposing non-target parasites to chemicals (e.g. products to treat tick or lice can also affect worms).
• The long-term protection provided by insecticidal tags also increases selection for resistance. It is therefore particularly important to implement a resistance management program when using ear tags.
• In Australia, resistance to synthetic pyrethroids is widespread, resistance to organophosphates occurs in some areas and no resistance has been found to macrocyclic lactones.
• To reduce selection for resistance, use tags which contain different chemical groups in different years. Where resistance is known to be present to one group a two-year rotation of the other two tag groups may be necessary.
• Ensure that tags are removed after the protection period has expired (check label). Leaving them in longer exposes flies to sub-lethal doses of chemical and increases selection for resistance.
• If an early season treatment is necessary before the application of tags, or after tag protection has expired, use a spray or backline treatment containing a chemical group that is different to that in the tags.
• As chemicals used for treating lice, ticks or internal parasites can also select for resistance in buffalo flies, and vice versa, where practical use a different chemical group for different parasites.

What is resistance?

Pros

• Effective for up to 16 weeks.
• Nil withholding period (WHP) and export slaughter interval (ESI)

Cons

• Extra handling for tag application.
• Tags must be removed after protection time has elapsed and before sale for slaughter.
• Failure to remove tags may promote resistance.

Safety

• Very low risk of inadvertent chemical exposure If used according to label directions.

Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.

Other information

How it works

Insecticidal ear tags are moulded plastic tags that are impregnated with insecticide that is released slowly onto the surface of the tag by diffusion. ‘Grooming’ activities by the cattle in response to the flies rubs the tags on the shoulder, back and flanks of cattle and helps spread the insecticide over the animal. Some spread also occurs during contact between animals.

Chemical actives in fly tags sold in Australia are from three insecticide groups, synthetic pyrethroids (SPs), organophosphates (OPs) and macrocyclic lactones (MLs) (see Table 1)

Activity

Insecticidal ear tags can give up to 16 weeks protection against buffalo flies, depending on the type of tag and whether or not there is any resistance to the chemical active in flies on your property.

Because only small doses of chemical are released daily the chemicals are not absorbed into meat or milk. Therefore, most ear tags have nil meat and milk withholding periods and don’t pose a threat to dung beetles. However, note that ear tags containing abamectin have an export-slaughter interval of 42 days.

Application

Tags should be applied to the animals in a similar fashion to an identification tag, between the second and third rib cartilage of the ear taking care not to penetrate the cartilage or any blood vessels (Figure 1). Use purpose-designed applicator pliers and ensure the tag body is attached on the back of the ear. A new product, Python Insecticidal Cattle Strips, which can be attached to existing ear tag studs and doesn’t require insertion of a new tag has also recently been registered in Australia (see Table 1).

All tags must be removed before cattle are sent for slaughter.

Table 1. Ear tags registered for control of buffalo flies in Australia