In the course of an interesting lecture at the conference of stock inspectors in Sydney last week, the N.S.W. government entomologist (Mr. W. W. Froggatt) described in detail the experiments for the control of sheep-fly conducted by the Department of Agriculture and a committee of pastoralists under his supervision. This work (he said) had been proceeding for the past six years, and field camps had been established at various times at Brewarrina, Salisbury Court (Urala), Wooloondool (Hay), Kooroogama (Moree), and Warrah. Extensive work in trapping the sheep flies had been undertaken at Warrah, an area of 10,050 acres of typical Liverpool Plains country having been granted by Messrs. Henry and Halloway. On this area a hundred departmental fly-traps had been set out at intervals of half a mile, and each had been baited with ½-lb. of bullock's liver and a quart of water. These were visited by an officer every ten days, and water or liver added as required. The contents were not removed until they came close to the bottom of the gauze funnel as it had been found that the decaying flies increased the attractiveness of the bait. The results of the trapping had proved very interesting, and from the start flies had been attracted, although in the open forest the flies were not at first so active as on the plains. Whenever there was stock in the paddock or near water the flies were most active. The traps had been cleared twice, and at a very low estimate each had accounted for an average of 100,000 adult flies, making a total of ten million flies over the experimental area. But it had not yet been discovered where the flies bred, and except at the sheep yards when drafting, and at the traps, no flies could be found.
They had swept the grass and the gullies with nets at all hours of the day, and could find no blowflies. At Warrah last month the sheep began to show signs of having been blown, and numbers of green flies followed the sheep into the yards. It was found that when the sheep were in the open the flies would be attracted away from the sheep, but under the covered yards and races the smell of the sheep was too strong, and the flies remained on the animals.
Mr. Froggatt estimated that even in rough country, a man with a spring cart and two horses could attend to 100 traps all the year round. Apart from liver, rabbits or meat of any kind could be used as bait. He referred to the work of parasite breeding and distribution, and stated that at the veterinary experiment station at Glenfield, twenty or more packets were made up weekly, each containing about 2,000 parasitised fly pupae. But although the parasite was handy and efficient, it would never extirpate the blowfly. But it could be claimed that if artificially assisted, the chaleid wasp would be a big factor in reducing the number of the flies. Merino sheep would have to be properly crutched if they were to be freed from fly, and more care would have to be taken with the paddock supervision during the fly season. In good seasons it would possibly pay to spray with an arsenic solution as a preventative measure. Many statements had been made by those interested in sheep licks that healthy sheep were not likely to become blown, but his experience was that when the wool of healthy sheep became evil smelling they would be as badly blown as unhealthy ones.