South-western WA

While you may be researching or planning a program for a specific parasite that is a problem for your property, it pays to be aware of what other parasite risks may be approaching and make an integrated plan.

Programs for the key parasites, ticks, buffalo fly, lice, worms and fluke can be opened below. The recommendations are generic and therefore need to be customised to the needs of individual producers and delivered by those with knowledge in the field.

Be aware that chemical resistance can develop in both targeted and non-targeted parasites.

Use of chemicals to control one type of parasite can also unintentionally select for resistance in a different group of parasites. It is important to read the label to determine which parasites will be controlled. Resistance is a significant issue in ticks, buffalo flies and cattle worms. When choosing a chemical to control one of these parasites, consider the possible side effects of increasing selection for resistance to the others.

Strategies for delaying the emergence of chemical resistance include:

  • Where possible include non-chemical control strategies to reduce reliance on chemical treatments.
  • Avoid frequent use of the same chemical or chemicals within the same chemical group.
  • Don’t under-dose products as this allows the more tolerant pests in a population to survive. Common causes of under-dosing include under-estimating the weight of animals being treated, poor application technique, and mis-calibrated application equipment.
  • Use chemicals according to the product label.

Read more:


Highest WECs

​  Autumn

Significant worms

​  Small brown stomach worm (Ostertagia ostertagi)

​  Barber’s pole worm (Haemonchus placei)

​  Small intestinal worms (Cooperia species)

Other worms

​  Nodule worm (Oesophagostomum radiatum)

​  Stomach hair worm (Trichostrongylus axei)

Calendar for worm and fluke control

Table 1. Calendar for worm and fluke control.

Class of Cattle

Time of year



Autumn born weaners/yearlings



Spring born weaners/yearlings

Drench at weaning (Mar-Apr)

Heifers/unsold yearlings



Adult cows

Adult cows usually develop a strong immunity to roundworms so mob-scale drenching should not be required – individual cows showing reduced weight gains or signs of internal parasitism (diarrhoea, low body condition score, ill-thrift or high WEC) should be treated.


Drench 7 weeks prior to joining


Strategic worm treatment given each year


Not a routine treatment. Indicators for treatment include scouring, sudden loss of condition and a condition score of 2 or less, especially if feed availability is less than 1,000kg DM/ha. Treatment will be more effective if combined with a change to ‘low-risk’ pastures, especially for young stock.


Both adult and immature fluke present – select a drench that kills all fluke stages


Adult and immature fluke present. This drench may not be needed on properties with a low fluke risk.


Only adult fluke present. Use a drench other than triclabendazole to help slow the development of resistance.



Buffalo flies Stable flies

  • Climate largely unsuitable for buffalo fly.
  • Stable flies have become a significant problem in some areas of the Swan valley and cattle may require protective treatments.


Seasonal trends

Louse numbers increase

early winter  early spring

Optimal timing of treatment if needed (usually not required)

early winter

Lice numbers increase from early winter through to early spring and then decline with increasing temperatures in spring and summer. Heavy infestations are usually seen in cattle in poor body condition. In most cases the lice are a consequence, and not the cause, of poor nutritional conditions. Where lice are an on-going problem a single treatment in early winter will usually provide effective control.


Cattle tick is not a problem in this region

Problem ticks

  • Bush tick rise in spring or with wet season, adults most numerous in spring and summer. Routine control measures for bush tick are generally not warranted.