Ear-tags impregnated with insecticides are plastic tags that are fixed to the ears of cattle for the control of parasitic insects, mainly flies

The plastic used for manufacturing is mixed with a given insecticide before hardening in the form-giving mold. When fixed to the ears of cattle the plastic progressively releases the insecticide, which spreads throughout the hair coat.

Typical insecticidal ear-tag.

Such ear-tags are applied to the animal's ears using a special applicator in the same way as identification tags .

Insecticide-impregnated ear-tags are mostly flag shaped tags of different colors.

Insecticide-impregnated ear-tags are used on cattle mainly to control horn flies (Haematobia irritans). They don't control the major tick species ticks nor mites, and do not protect against various cutaneous myiasis (e.g. screwworm, cattle grubs, etc.), mosquitoes and horse or deer flies.

Some ear-tags may help to control other parasitic flies (e.g. stable flies or face flies) and a few lice species.

Insecticide-impregnated ear-tags are especially useful for range or pasture cattle under extensive farming conditions for which horn flies are the major pest and other parasitic flies play only a secondary role.

For cattle kept under intensive farming conditions or for dairy cows stable flies are equally or even more important than horn flies and consequently insecticide-impregnated ear-tags are usually not enough to control flies. Additional control measures may be required, depending on the fly species that cause the problem.

There are a few insecticide-impregnated ear-tags for sheep or pig as well, but not for dogs or cats. Insecticde-impregnated collars use the same technologies for plastic or tissue impregnation with an insecticide that is progressively released and spreads throughout the hair coat to protect the animal against various parasites.

Active ingredients used in ear-tags

So far only organophosphates (e.g. diazinonchlorpyrifos) or synthetic pyrethroids (e.g. cypermethrin, permethrin) are used to impregnate ear-tags. All these active ingredients are non-systemic contact insecticides. Recently a few tags with abamectin, a macrocyclic lactone, have been introduced in some countries.

If the flies are susceptible, i.e. not resistant, these tags can protect cattle against horn flies for three months and longer. Length of protection depends on the compound the tags are impregnated with and on its concentration.

Unfortunately resistance of horn flies to synthetic pyrethroids is quite frequent worldwide and often very high. Protection against resistant flies will be significantly shorter, depending on the resistance factor, and even nil against highly resistant flies. There are also organophosphate resistant horn fly populations, but resistance levels are usually lower.

Correct use of insecticidal ear-tags

It is important to correctly apply the ear-tags to the ear lobes, otherwise they can get stuck on fences, tree branches, etc., tear the ear lobes and get lost. To ensure the proper transfer of the released active ingredient to the rest of the body it is important to fix the ear-tag in a way that part of it overhangs the ear lobe. But not too close to the border of the ear lobe, because it can easily tear.

Three to four months after application the old ear-tags have to be taken off because they do not release enough active ingredient to control the flies. If this is not done, it results in under dosing, i.e. the flies remain exposed to sub-lethal concentrations, and this favors resistance development. For dairy cows, applying and taking off the ear-tags must be repeated many times and it is recommended to fix an ear-tag on the same perforation as the previous one, although this is not always easy to do. 

Depending on the particular brand, two tags (one on each ear) or only one tag have to be applied. Usually, for ear-tags containing aprox. 40% of an insecticide only one tag is needed per animal, whereas for those with aprox. 20% insecticide two tags per animal are needed. If two tags are required, applying only one must be avoided. It may initially work, but protection will be shorter and underdosing is likely to result, which favors resistance development. The same is true if only part instead of all the animals in a herd are tagged. It is true that untagged cattle will get some insecticide through contact with tagged animals. But this means that both tagged and untagged animals will be underdosed.

Pros and cons of ear-tags

The major advantage of ear-tags is the long protection against the damaging horn flies and the corresponding fewer musterings for treatment.

Being ready-to use, there are no risks of mistakes when diluting concentrated products for dipping or spraying, or of poisoning of livestock and operators with highly concentrated pesticides.

Ear-tags are quite flexible regarding when to treat. In contrast with pour-ons they can be applied by rainy and windy weather. In numerous countries insecticide-impregnated ear-tags are approved for use on dairy cattle, which is not the case for pour-ons with most macrocyclic lactones (e.g. abamectin, doramectin, ivermectin, moxidectin) and fipronil, often used for horn fly protection in many regions.

The major inconvenience of ear-tags is the bothersome tagging and detagging that requires a cattle crush or chute to restrain the animals, which can be too stressing for some pregnant or otherwise weakened animals.

Most used insecticidal ear-tag brands

(Focus in the US, UK and Australia)

Country differences may apply: read the product label!

Selection of most used INSECTICIDE EAR-TAGS for CATTLE
Brand Weight (g) Pests Countries Tags*
With Synthetic Pyrethroids (all isomer mixtures)
Cyfluthrin (%) [+ synergist %]
Cylence Ultra (8%) + [20%] 14.17 Fly, Ti US, AU 1-2
Cyhalothrin (%) [+ synergist %]
Saber Extra (10%) + [13%] 9.5 Fly US, AU 2
Cypermethrin (%) [+ synergist %]
Flectron (8.5%) 11 Fly UK + EU 1-2
Phyton (10%) 9.5 Fly, Li, Ti US, AU 1-2
Phyton Magnum (10%) + [20%] 14.5 Fly, Li US 1
Phyton Maxima (10%) + [20%] 14.5 Fly, Li AU, NZ 1
Permethrin (%) [+ synergist %]
Auriplak (10%) 12 Fly UK + EU 1-2
GardStar Plus (10%) 9.5 Fly, Li, Ti US 1-2
With Organophosphates
Diazinon (%)
Optimizer (20%) 15 Fly, Li, Ti US, AU, CA 2
Patriot (40%) 15 Fly, Li, Ti US, AU 1
Diazinon (%) + coumaphos (%)
Co-Ral (20%) + (20%) n.a. Fly AU 2
Corathon (35%) + (15%) 14 Fly, Li US 1-2
Diazinon (%) + chlorpyrifos (%)
Warrior (20%) + (10%) 15 Fly, Li, Ti US, AU 1-2
Pirimiphos-methyl (%)
Dominator (20%) 9.5 Fly US 2
Tetrachlorvinphos (%)
Rabon (13.7%) 16.5 Fly AU 1-2
With Macrocyclic lactones
Abamectin (%) [+ synergist %]
Agressor (8%) + [18%] 9 Fly AU 2
XP 820 (8%) + [20%] 9 Fly, Ti US 1-2
With Mixtures of Chemical Classes
Cyhalothrin (%) + Pirimiphos-methyl (%)
Double Barrel (6.8%) + (14%) 9.5 Fly US 2

* Recommended number of tags / animal

Country differences may apply: read the product label!