Subtropical Coastal QLD

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.

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Lice on cattle are generally not an economic problem. Only treat when heavily infested as indicated by rubbing on fences or structures.

Seasonal trends

Louse numbers increase

late autumn  early spring

Optimal timing of treatment if needed (heavy infestation)

late autumn

Louse numbers increase from late autumn 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 late autumn will usually provide effective control.


Buffalo flies

  • Treat if buffalo flies are above threshold numbers before Christmas, or after ear tags have expired (apply an OP spray or a pour-on from a different chemical group to that oftags). Industry threshold numbers are:

Beef animals. 200 flies

Dairy animals. 30 flies

  • Apply insecticidal tags when flies are above economic thresholds in January.
  • Remove tags when they expire (Check label; 16 weeks for most tags) to avoid selecting for resistance.
  • Use ear tags from different chemical groups in successive years (OP, SP, ML).
  • Consider using buffalo fly traps or backrubbers.


Cattle tick Paralysis tick Bush tick

Seasonal trends

  • Cattle tick most active December through June.
  • Paralysis tick most active July through December, adults peaking in spring (normal calving time). Young calves are particularly susceptible to paralysis tick toxin so if your property is in a paralysis tick area, consider treatment before paralysis ticks can inject a lethal dose of toxin.
  • 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.

Optimal timing of cattle tick treatment if needed

Start of spring

  • Start cattle tick treatments early, before tick numbers build.
  • Add additional treatments roughly every 3 to 8 weeks (varies depending on the product and application method; follow the product label and take note of withholding periods), or if 20 or more adult ticks >5mm are seen on one side of several animals. The need for treatment will depend on conditions (e.g. fewer ticks in hot, dry years), time of year (start or end of tick season) and the ability to monitor your animals.
  • Plunge dip, race spray, or pour-on: 5 treatments with 3 week intervals.
  • Injectable: follow the product label: 4 treatments with 4 week intervals OR if long acting, 2 treatments with an 8 week interval.
  • ML drench; apply at start of tick season in place of 1 dip or spray.
  • End treatments late in the tick season to lower the number of tick eggs released onto the pasture before the dry season (these end of season eggs develop into next season’s ticks).
  • Vaccinate all cattle against tick fever at three to nine months of age (often convenient at weaning).


Highest WECs

​  Autumn

Significant worms

​  Barber’s pole worm (Haemonchus placei)

​  Small intestinal worms (Cooperia species)

Other worms

​  Nodule worm (Oesophagostomum radiatum)

​  Small brown stomach worm (Ostertagia ostertagi)

​  Stomach hair worm (Trichostrongylus axei)

​  Stomach fluke (Calicophoron calicophorum)

​  Liver fluke

Calendar for worm and fluke control

Table 1. Calendar for worm and fluke control.

Age group








Yearlings/First calvers

() Pre-calving



2nd calvers


() Pre-calving



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.






Liver Fluke control

All weaned cattle





Stomach fluke control

A single treatment of all weaned cattle in Sep will usually control stomach fluke in ‘flukey’ areas e.g. swamps, inundated areas, river flood plains. In some cases an additional treatment may be required in Mar-May based on monitoring and veterinary advice.


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.