Company: COOPERS

FORMULATION: concentrate for topical administration to sheep by «dipping» or «jetting»

ACTIVE INGREDIENT(S): Diflubenzuron: 250 g/L (= 25%)

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.


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


  • Plunge and Shower Dipping:
    • Ewes, hoggets and rams: 150 mL product in 100 L water (equivalent to 375 ppm = mg/L difubenzuron in the wash).
    • Lambs (medium-term fly control): 150 mL product in 100 L water (equivalent to 375 ppm = mg/L difubenzuron in the wash).
    • Lambs (long-term fly control): 250 mL product in 100 L water (equivaletn to 625 ppm= mg/L difubenzuron in the wash).
  • Jetting:
    • All sheep: 250 mL product in 100 L water (equivalent to 625 ppm= mg/L difubenzuron in the wash).
  • The length of protection may be affected by factors such as weather, wool type, skin, wool diseases (mycotic dermatitis or fleece rot) and soiling of wool especially from dags.


  • Plunge and Shower Dipping:
    • 14-35 days post shearing: 60 mL product in 100 L water (equivalent to 150 ppm = mg/L difubenzuron in the wash).
    • >35 days post shearing: 150 mL product in 100 L water (equivalent to 375 ppm = mg/L difubenzuron in the wash).
  • For lice control, apply as plunge, shower dip or jetting to sheep with short wool. Optimum time for application is 14-35 days after clean-shearing or 14-28 days after cover-comb shearing.

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


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

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

  • Meat: New Zealand: NIL
  • Milk for human consumption: New Zealand: Milk intended for sale for human consumption must be discarded during treatment and for not less than 35 days following the last treatment.
  • Wool: New Zealand: 2 months.

WARNING !!!: Never use on humans, dogs or cats.

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


Risk of resistance? HIGH

Resistance of blowfly strike to diflubenzuron and other benzoylphenyl-ureas is widespread in Australia and New Zealand. Resistance of body lice (Bovicola = Damalinia ovis) to diflubenzuron and other benzoylphenyl-ureas has been reported in Australia, but seems not be a problem yet in New Zealand.

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 to prevent resistance of through product rotation:

These alternative products may not be available in all countries, or may not be available for dipping, jetting or dressing.

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: New Zealand
GENERIC BRANDS available? Yes, several ones in New Zealand and Australia.

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

Click here for an overview on the most used antiparasitic BRANDS witoncentrates for dipping, spraying, or jetting.


ZENITH CONCENTRATE for sheep from COOPERS is a classic concentrate for dipping and jetting sheep containing diflubenzuron.

Diflubenzuron is a veteran IGR, the first benzoylphenyl-urea, discovered already in the 1970s (by PHILIPS-DUPHAR). It is a so-called Chitin Synthesis Inhibitor (CSI) effective against numerous insect species. It is moderately used in sheep, very scarcely in other livestock but not in pets. It is also moderately used in agricultural pesticides. 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.

Chitin is a component of the cuticle of insects, which is an essential part of their outer skeleton. If chitin is not properly produced, larvae die when they attempt the next molt. The consequence is that fly maggots cannot complete molting and die. CSIs such as the benzoylphenyl ureas (BPUs, e.g. diflubenzuron, triflumuron) inhibit chitin synthesis. But they do not immediately kill the fly maggots (larvae), i.e. they have no knockdown effect. Larvae will die at their next attempt to molt to the next developmental stage, which may take 1-4 days to occur, depending on age of the maggots at the time of treatment, humidity, temperature, etc. For this reason, IGRs are usually not used for curing established strikes, but for preventing their development by killing the very small first-stage larvae that hatch out of the eggs deposited by the adult flies on the wool.


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.