Company: WSD

FORMULATION: wettable powder concentrate for topical administration as a «dip»


  • Rotenone: 1.3% (= 13 g/L)
  • Magnesium fluorosilicate: 40% (= 400 mg/)
  • Sulphur: 25% (= 250 mg/L)

CHEMICAL CLASS of the active ingredient(s):

  • Rotenone: Natural insecticide
  • Magnesium fluorosilicate: Mineral insecticide
  • Sulphur: Mineral insecticide

INDICATIONS: SHEEP: after shearing for up to 6 weeks off-shears

PARASITES CONTROLLED (spectrum of activity)

  • Sheep body lice Bovicola (Damalinia) ovis.  
  • Itch mite, Psorergates ovis
  • Keds, Melophagus ovinus
  • Mycotic dermatitis due to Dermatophilus congolensis.


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

  • 1.25 kg (one bag)/500 L water for all dip types (dilution 1:400). Replenish at the same rate.
    • Plunge dips: add 1.25 kg after a drop of 500 L for plunge dips.
    • Conventional shower dips: add 1.25 kg plus 500L water when addition of water is required; no reinforcement is necessary

Plunge Dipping. Ensure the correct amount of product is added to the volume of water in the dip. Agitate the dip wash before, during and after treatment groups. Ensure animals are in the dip for a minimum of 30 seconds, and plunge their heads under water at least 3 times. After sheep leave the dip, they should be segregated from undipped animals. The dip should be replenished regularly as the level falls.

Shower Dipping. Ensure the correct amount of product is added to the volume of water in the tank and sump. It is preferable to use a continuous replenishment system. When using a shower dip it is essential to ensure adequate wetting by sufficient nozzle pressure and time in the shower. This may be up to 12 minutes of treatment at 75 psi delivered to the overhead nozzles. It is advisable to include a pressure gauge in the line. The use of floor mounted nozzles is not necessary and this can reduce overall nozzle pressure. Sheep should also be checked to ensure wetting has occurred through to the skin of the animal. Treated animals should be segregated from untreated animals after dipping.

Hand-Jetting. To manage and control lice infestations in sheep with more than 6 weeks and less than 6 months wool. Ensure Flockmaster MK II is used at the recommended rate on the label and do not under dose. Mix well and keep the dip-wash agitated in the tank by a return valve from the pump. It is essential that there is adequate pressure from the handpiece or nozzle(s) to wet the skin of the animal. WSD recommends a 4 Horse Power pump with minimum hose sizes of 1.5 inches (38mm) from the tank to the pump, and ¾ inch (19mm) from pump to handpiece. The handpiece or nozzle must be capable of delivering a minimum of 15 litres in 30 seconds. To test pressure and delivery of a system, measure the quantity of water delivered into a marked bucket in 30 seconds. Sheep should be jetted as two strips from the poll down either side of the back and also under the neck.


  • Oral LD50, rat, acute, for rotenone: 40-1500 mg/kg, depending on the vehicle
  • Dermal LD50, rat, acute, for rotenone: >5000 mg/kg

In the last years several studies seem to confirm a link between high exposure to rotenone and Parkinson's disease in humans, and several countries have limited the usages of rotenone products for safety reasons.

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

  • Meat: Australia 1 day (ESI 1 day)
  • Milk for human consumption: Australia: Not for use in sheep producing milk for human consumption.
  • Wool: Australia: NIL (0 days).

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? LOW. No resistance of sheep body lice or other veterinary parasites has been reported for rotenone, nor to magnesium fluorosilicate or sulphur. 

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it is likely to be due to incorrect use rather than to a resistance problem. Incorrect use is usually the most frequent cause of product failure.

However, uninterrupted use of any active ingredient against sheep body lice for years is likely to result in resistant lice. For this reason rotation with other chemical classes is highly recommended.

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

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? very few, if at all. Rotenone is a natural insecticide obtained from plants; magnesium fluorosilicate and sulphur are mineral products. Neitehr of these constituents is patent protected.

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

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


WSD FLOCKMASTER MK II for sheep from WSD is one of the very few products for sheep containing natural ingredients, i.e. non-synthetic insecticides. 

Rotenone is a natural compound extracted from the roots of several plants such as Derris spp. (native to Asia), Lonchocarpus spp. (native to South America) and other related plants. It is toxic to many insects and fish species. These properties of the natural extract were already known in the 17th century. Some indigenous populations in Asia and Latin America use the toxic effect on fish for fishing. They grind leaves or roots of the plants, throw the extract into the river, and collect the stunned fish downstream. Usage on livestock and pets has been and remains marginal. Rotenone is oxidated by sunlight, which reduces the length of protection against external parasites after topical administration.

Magnesium fluorosilicate is a mineral product that kills some insects by absorbing the lipids of their cuticle, which accelerates water loss and results in dissication. However, efficacy is usually not sufficient to eliminate established parasite populations. Is only marginally used against agricultural or veterinary pests, e.g. in some products against poultry mites.

Sulphur has been used since ancient times against several pests of livestock and crops. It does not have a strong impact on insects, but helps controlling mycotic infections.

All these natural ingredients leave very low residues in wool and body tissues, which allows very short withholding periods.


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.