WAR ON FLIES

Press, Volume LXXX, Issue 24329, 7 August 1944, Page 6

WAR ON FLIES

OVERSEAS PROMOTIONS.—LEFT: Sub-Lieutenant D. N. Graham, of Christchurch, who has received his commission in the Fleet Air Arm. He passed out top of his class in Canada, with a special distinction pass, and was awarded the Admiralty prize. RIGHT: Second-Lieu-tenant A. Brooke-Taylor, son of Mr and Mrs J. Brooke-Taylor, New Brighton, who has gained his commission in England after three and a half years’ active service in the Middle East.

CONTINUOUS EFFORTS URGED “POTENT CARRIERS OF DISEASE ” The importance of educating all members of the public to their individual responsibility to wage unremitting warfare on flies was emphasised by Dr. R. A. Falla, director of the Canterbury Museum, in an address to the local body sanitary inspectors' conference, held in Christchurch. In certain circumstances, he said, they were very potent carriers of disease and contaminators of food.

Spasmodic efforts at control were useless, said Dr. Falla, because the life cyde of the house-fly was so short—about 10 da'ys in ideal conditions. During the rat campaign in Christchurch emphasis had rightly been laid upon the extermination measures being *a continuous process, and this applied with even greater force to measures against flies. The common house-fly was not a native of New Zealand, said Dr. Falla, but* its introduction was so early that there was no historical record, of it. The lesser house-fly, the biting housefly, the stable fly, the cluster fly (which was frequently active in winter), and two or three species of blue-bottles were also found in New Zealand. The common house-fly could be identified by the elbow-like vein pattern in the wings, which swept backward in a V. There were four distinctive markings on the back and another identification point was the wide space between the eyes. Breeding Grounds Dr. Falla added that the common house-fly was a purely mechanical carrier of disease and did not go through a cycle of infection, as the anopheles mosquito did. It bred chiefly in decaying organic material, although it had a preference for stable manure The female might lay five or six batches of 150 eggs each in a season, and it was estimated that in 151b of stable manure there was enough edible material to enable 10,000 maggots to reach maturity. The elimination of breeding places by the frequent removal of refuse and the covering of all receptacles containing suitable breeding site materials was advocated by Dr. Falla as a prime method of control. Fly-proof covers for food should be used, and he emphasised that the covers should not touch the food, as flies might deposit eggs through the mesh of the cover. As the inside of heaps of organic material was usually too hot for breeding, flies laid their eggs only in the outer layers. If the surface of such heaps were turned and compacted every three days or so the eggs would not come to maturity. Traps and Poisons Adult flies gould be destroyed - by traps, flypapers, and poisons. Fpr the latter, curved surfaces were desirable, and the trap should be baited with a few flies Suitable poisons were two teaspoons of formalin and two tablespoons of sugar to a pint of limewater. and three teaspoons of sodium salycilate to a pint of water. Sprays were effective provided the essential ingre-’ dient, an extract of pyrethrum, was of adequate strength. The kerosene base of such sprays would in itseli stun flies but the pyrethrum extract was the lethal agent. A new and very powerful insecticide, the chemical formula of which was known as D.D.T., had been developed in the United States, and could be expected to be released for civilian use shortly, said Dr. Falla. A room sprayed with this insecticide would remain lethal to flies for three months. Flies did not generally travel 'far, so long as food and breeding places were available near at hand, said Dr. Falla The probable maximum distance in town areas was a mile, and in country areas, in exceptional circumstances, up to 13 miles. , tl „ . “In spite of all the study that has been given to this subject in all parts of the world, we still do not know where flies go to in the winter time concluded Dr. Falla. He added that the ability of flies to survive the severe winter of such a place as Labrador was a mystery to scientists, although it was evident that a certain residue of one generation must be carried over from one season to the next