FORMULATION: concentrate for dipping and jetting.

ACTIVE INGREDIENT(S)diflubenzuron 25 g/L (= 2.5%)

CHEMICAL CLASS of the active ingredient(s): insect growth regulator (= IGR, benzoylphenyl urea)


PARASITES CONTROLLED* (spectrum of activity)

* Country-specific differences may apply: read the product label.

  • Control and treatment of body lice Bovicola (Damalinia) ovis
  • Can be used on short or long woolled sheep (with up to 6 months wool).


* Read the product label for further details on dosing and administration.

Use recommendations (off-shears, Australia): 150 mL per 100L


  • LD50 (acute oral) in rats: >4640 mg/kg for the a.i. (source: MSDS)
  • LD50 (acute dermal) in rats: >10000 mg/kg for the a.i. (source: MSDS)
  • Estimated hazard class of the a.i. according to the WHO classification of pesticides: U, unlikely to present acute hazard in normal use.

Withholding periods (=withdrawal times) for meat, milk & shearing (country-specific differences may apply: read the product label)

  • Meat: Australia: NIL
  • Milk: Australia: NIL
  • Shearing: Australia: 6 months before shearing or fibre collection.

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


Risk of resistance in BODY LICE? YES, in sheep. Resistance reported in Australia in field populations.

Resistance of body lice Bovicola (Damalinia) ovis to diflubenzuron and other benzoylphenyl ureas has been reported in Australia and it must be expected to increase. For this reason efficacy of this product against sheep body lice may not achieve the label claims. Resistance of sheep body lice to synthetic pyrethroids is also high and widespread in Australia. For this reason compounds of this chemical class are no more approved for lice control in Australia.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it may be due to resistance and not to incorrect use, which is usually the most frequent cause of product failure.

Alternative chemical classes/active ingredients for product rotation to prevent resistance of body lice to triflumuron:

These alternative products may not be available in all countries, or may not be available as pour-ons.

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or GENERICS**?


*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this brand/product is marketed: Australia.
GENERIC BRANDS available? YES, a few ones in Australia.

Click here to learn more about GENERIC vs. ORIGINAL drugs.

For an overview on the most used antiparasitic pour-on brands click here.


STRIKE is a lousicide from COOPERS (MERCK AH - INTERVET) containing generic diflubenzuron.

Diflubenzuron is a veteran IGR, the first benzoylphenyl urea discovered already in the 1970s (by PHILIPS-DUPHAR). It is scarcely used in livestock and agriculture, but not in pets. It was introduced for use as a lousicide in sheep in Australia only in the 1990's (under the TM FLEECARE from HOECHST), when lice developed high resistance to synthetic pyrethroids, which lost approval for lice control. Diflubenzuron and other benzoylphenyl ureas subsequently conquered the sheep body lice market very quickly in Australia after resistance to synthetic pyrethroids exploded and organophosphates that still worked well were progressively withdrawn for safety reasons.

It is important to understand that this and other products containing insect growth regulators do not kill adult lice that may infect sheep or cattle at the time of treatment, i.e. they don't have a knock-down effect. What they do is to prevent development of immature stages. Larvae and/or nymphs fail to molt to the next stage and die. Therefore they are used to prevent the further development of immature stages or eggs of occasional adult lice that sheep may catch.

It is interesting to know that neither diflubenzuron nor other benzoylphenyl ureas are used on sheep in the EU, the US or in Latin America, where body lice is also an important pest of sheep. The likely reason is that organophosphates and/or synthetic pyrethroids are still widely used in these countries against this pest that has not yet become resistant to these chemicals there.


This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional.