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Australia's resource for control of worms, flies and lice in sheep,
and worms in goats

Fast Fact: Sex-changing, tongue-eating lice

Imagine a louse that starts its life as a male and once mature, is stimulated by another male to change sex and become a female. Now picture that female louse climbing right into the mouth of the host it's inhabited and attaching herself to its tongue. She then pierces the tongue and feeds on it by sucking out the blood, causing the tongue to atrophy and fall off. How does the host now function without a tongue? Amazingly, this is the only known parasite that can functionally replace a host organ, because that louse now acts as an organic prosthetic, replacing the tongue she ate. Any younger male parasites now climb into the host’s mouth and mate with the female who then produces a cast of male juveniles that start the whole cycle again. Fortunately, you will only find the louse in question, Cymothea exigua, on fish, not on your sheep or yourself. 

Feature articles

How are Australian sheep producers managing worms?
Results of the Australian Sheep Parasite Survey 2019

by Alison Colvin, Universtiy of New England

Many worm control practices have seen only minor changes since the 2003 and 2011 surveys. There was little application of methods for prolonging drench life such as harnessing refugia on pasture by leaving some sheep undrenched, using new drench actives, using Barbervax® in summer rainfall regions or breeding for resistance using ASBV-WEC. However, there was good implementation of grazing management for worm control, particularly the use of preparing clean pastures by spelling paddocks. The usefulness of preparing clean pastures by spelling paddocks is entirely dependent upon the length of the spelling period and the season in which it is used. The methods and timing also vary across regions.

There was an upward trend in the use of WEC monitoring since 2011, despite the dry conditions in the 2018 survey. The top 3 drench actives used were the same in 2018 and 2011 with very low uptake of newer drench actives. There was a small upward trend in respondents conducting drench tests over 5 years, but still low proportions conducting drench tests overall, leaving producers unaware of their drench resistance status. >> Read more.

Lice treatment frustrations

by Deb Maxwell, ParaBoss

A farmer I visited last year was keen to get rid of lice, and had sorted out some obvious issues such as a poor section of boundary fence, but after a couple of years he was still finding complete eradication elusive. Eradication is so easy in theory because all lice are on the sheep (just think if we all really stayed home for a month—Covid-19 would be gone before you know it), but it’s never quite so simple in practice.

I showed him the LiceBoss Treatment Tool and we went through the simple questions about shearing and treatments in just a few minutes—we only needed to select from the ready-made answers to each question. The report provided a short checklist highlighting the issues that needed attention. In his case, a split shearing and one not quite good enough internal fence was the issue. >> Try out the LiceBoss Treatment Tool for yourself.

Have organic farmers got anything to teach the non-organic farmer?

In one of the Wormcasts (Paraboss podcasts) by Susan Swaney and Ian Campbell, they discuss organic farming of livestock and how organic farms manage their parasites. The question is: are there some lessons in there for those of us who run conventional farms?

Here is Ian's limerick for the podcast.

Organic farming is grouse
But don’t get a worm, fly or louse
'Cos a drench or a dip
Or a tail fold nip
They won’t let those things near your house

>> Go to Wormcast No. 10 to find out more.

Flystrike: But I treated them!

by Deb Maxwell, ParaBoss

An old friend of mine who has only been running sheep for the last 5 years, called me, perplexed that some of his sheep were flystruck despite having had a flystrike preventative product applied to them. He had counted out the time of the label claim from when his sheep were treated and believed they would be completely protected right through till then. However, it’s not as simple as that.

Next time you have some flystrike product at hand, check the label; most have a claim that is “up to” a certain number of weeks, and for very good reason. One of those reasons is resistance to chemicals. But don’t jump to conclusions! More often than not earlier than anticipated strike is due to one of the other reasons, which should be checked out first before you assume it’s resistance. >> Find out those reasons.


What are Aussie farmers doing for worm control?
Find out why lice eradication is elusive
What can organic farmers teach the rest of us?
Reasons why sheep get struck, despite treatment
Wormcasts: Paraboss podcasts
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