Communal Farming

Maggot infestation from flies can lead to major problems in a flock. The condition can be treated, but prevention is more effective, and considerably easier.

Many sheep farmers don’t realise that flies can cause serious financial loss. If left untreated, maggot infestation from flies can result in fever and infection, leading to a lack of appetite. This in turn will cause the animal’s body condition to deteriorate. The wool will also become matted, greatly reducing its value.

Severe infestation can lead to severe blood loss, tissue damage, and even death.

The main culprits of fly strike are bluebottle, blackbottle, and greenbottle flies. These lay their eggs in moist and dirty areas, such as decaying flesh, open wounds and manure. Over two to three weeks, the eggs hatch maggots, which then pupate into adult flies.

To avoid a major infestation, you need to make sure that manure heaps do not stay wet, as these can quickly become maggot breeding grounds. Open the heaps up with a rake and allow the manure to dry out before ploughing it into gardens or croplands as fertiliser.

Remember that although flies may not be active in winter, their eggs lie dormant in the soil and hatch into larvae in spring or summer when the temperature increases and the soil is moistened by rain.

prevention

Hang a few plastic fly traps around areas where manure tends to build up. These are a great help for controlling the fly population on your property. Good fly baits are also available.

Walk through your flock regularly, looking for sheep that have separated from the flock and seem to be listless and depressed.

One of the clearest signs of fly strike is when an animal tries to lick or bite its tail region. Flies also attack the feet of a sheep with foot rot, and the animal will often try to bite its hooves as a result.

When sheep are placed on green feed or are suffering worm infestation, they can develop diarrhoea, which also attracts flies. If you see diarrhoea, treat the animal with a medication such as Sulfazine. If worm infestation is suspected, dose your sheep accordingly. Flies are also attracted to lambs with castration sores. The flies lay eggs in these sores or in the damp, soiled wool around the rectum of the sheep. On closer inspection, you may see large bunches of yellow fly eggs.

In advanced cases, large numbers of adult maggots may have already burrowed deeply into the skin to feed on muscle tissue.

treatment

Some medications can be rubbed onto the rear ends of sheep to help keep flies away, but these will not treat the condition once it has developed.

If the eggs and maggots are visible, you will need to ‘crutch’ the sheep. This means shearing the wool on the hindquarters down to the skin and about 5cm further than the border of the infection.

Sheep with severe wounds should be treated with an antibiotic injection

Use a dip wash to treat surrounding wool, and apply a healing spray that kills maggots and adult flies to any sores that have already formed. Use this for a few days to kill larvae that were still in egg form during the first treatment. Spray the area well and ensure the medication gets into all the little puncture wounds that may have been caused by maggots.

Sheep with severe wounds should also be treated with an antibiotic injection.

isolation and culling

Keep infected sheep isolated from the flock until they are totally recovered. Seal all maggots and infected wool for a few days in plastic bags treated with dip; this will kill the maggots.

Sheep that are continually weak from being attacked by flies should be culled from your flock, as infected sheep tend to attract flies, which then target unaffected sheep.

• Source: ‘Treatment of struck sheep’. 2018. Flyboss. Retrieved from www.flyboss.com.au/ treatment/treatment-of-struck-sheep.php.