Importance and impact of bush tick on cattle
- Economic loss due to theileriosis in disease endemic areas.
- Most infestations are relatively light and/or short-lived, however, the introduction of tick-naïve cattle into tick endemic areas can lead to heavy infestations with serious effects.
- Tick worry, which can significantly reduce cattle live-weight gain and milk production.
- Anaemia (blood loss).
Life cycle type
3 host tick. Larvae, nymphs and adults attach and feed on different hosts.
Cattle are the preferred host of bush tick, although large infestations have been found on deer. Bush tick often infests other livestock (including sheep and pigs), as well as other warm-blooded animals such as dogs, horses and even humans. It also occurs on numerous wildlife species, and the immature stages have been found on birds.
Average time spent on host
Larvae, nymphs and adults each attach and feed on a host for roughly one week then drop to the ground to moult or lay eggs.
- Engorged adult females fall from the host and lay around 3,000 eggs then die.
- Eggs take 60–90 days to hatch into larvae, depending on temperature and humidity.
- The larvae mature in 1 to 4 weeks then climb vegetation to quest for a host. Once attached to a host they feed for up to 6 days then drop to the ground.
- The engorged larva takes 3 to 6 weeks to moult into a nymph.
- 5 to 6 days after moulting, the nymphs attach to another host, feed for about a week, then drop to the ground.
- The engorged nymph takes 3 to 10 weeks to moult into an adult.
- Adults usually attach to a new host about 1 week later and feed for 6 to 21 days.
- Male bush ticks are seldom found and females can produce fertile eggs without the need for males.
- The full life cycle can be completed in as short as 4 months or as long as 18 months, depending on climate. In temperate climates with cold winters, usually only 1 generation occurs per year. In warm, humid climates, bush ticks can complete 2 to 3 generations per year.
Location on animal
- Bush ticks can attach anywhere, but they are generally found on less-exposed parts of the body that are more difficult to groom: ventral (underside) areas, such as the brisket, udder and inguinal region (groin), between the legs and around the tail, and very commonly in the ears.
- The immature stages (larvae and nymphs) are not easily seen and even adult ticks are easily missed when infestations are light, especially if they are not engorged. However, with heavy infestations the ticks occur all over the body.
Figure 1. Engorged bush tick Haemaphysalis longicornis. Image courtesy of Wikimedia CC.
Figure 2. Geographic distribution of the bush tick in Australia. Image adapted from Virbac.
The bush tick is found mostly in sub-tropical regions and some temperate areas with summer rainfall. In Australia, the main endemic zone is a relatively narrow coastal strip from southern Queensland (up to Gympie in the north) to the north coast of New South Wales, though the ticks may occur up to 100 km inland. It also occurs, though far more sporadically, as far south as Gippsland in Victoria, and inland as far as Albury-Wodonga. In Western Australia, a small area of infestation has established in the Walpole-Denmark district on the far south coast following an apparent introduction in the mid-1980s. Except in Queensland, where the far more important cattle tick occurs, ticks found on cattle in large numbers are usually bush ticks.
- Larvae rise in autumn.
- Nymph numbers peak autumn to spring.
- Adults are typically seen in largest numbers in spring and early summer. Seasonality is more pronounced in temperate climates with only a brief period of a few weeks for adult tick development in summer. This can appear as an ‘explosion’ of large tick populations on a particular property when susceptible animals encounter ideal conditions for tick development, followed by a rapid drop to insignificant numbers when hot and dry conditions return, or the pasture cover is reduced.
The best way to diagnose tick infestations before productivity losses occur is to regularly conduct tick screening. Adult stages are the only stage likely to cause disease and they are the easiest to identify due to their size (adult females are 3–10 mm).
Bush ticks can be distinguished from cattle tick and paralysis tick based on leg colour (bush tick legs are all a dark red-brown) and the position of the first pair of legs (in bush ticks the first pair of legs are located close to the ticks mouthparts). See the page on tick identification for more detail.
Follow these links to read more about bush tick treatment and management.