HOUSE SANDFLIES

Hauraki Plains Gazette, Volume 59, Issue 4252, 8 March 1950, Page 10

HOUSE SANDFLIES

NUISANCE AT TE AROHA METHODS OF CONTROL ETOMOLOGIST VISITS TOWN. The main reason for the sandfly nuisance at Te Aroha is, according to Cawthron Institute etomological officer, Mr. L. J. Dumbleton, the prolific growth on the banks of the Waihou river. Methods of controlling the pest were outlined by Mr. Dumbleton in a report to a recent meeting of the Te Aroha Chamber of Commerce.

Mr. Dumbleton, who spent three days at Te Aroha at the end of November, said that his investigation of the sandflies’ breeding habits at Te Aroha had revealed that the only species which found a breeding ground at Te Aroha was the Austrosimulium australense, which bred in large numbers in the Waihou river, and to a smaller extent in the small streams which discharged through the town on to the flats below the recreation ground (Herries park), Here they were breeding mainly on» watercress •and grasses. In the river tie bulk of the young stages (larvae and pupae) were found attached to willows and twigs dipping into the water, but they also occurred on sticks, roots and grasses hanging into the water.

“No sandfly breeding was found in the ponds and streams in the Government gardens nor in the rocky streams coming out of the bush above the town,” said Mr. Dumbleton. Clearing of Banka Advocated

“It is highly probable that the sandflies which cause annoyance in the town come from the river. The numbers of the sandflies breeding in the river could be reduced by cleaning up the banks—that is, cutting’back all* vegetation, especially willows, which dips into the river. It seems likely that most of the sandflies which occur in the town will have bred in the river close by the town and that under suitable conditions of wind they fly or drift up into the town. We have, however, no ihformatton on the flight range of these flies and it js possible that occasionally they may come in from further afield. It would probably be necessary to clean up about a mile of the river to have any effect

“Sandflies in other countries lyive recently been successfully controlled by using DDT in the streams, but we are not yet able to give you any recommendations as to dosage of DDT and frequency of treatment which could be applied to the Waihou river. In this connection the risk of damage to fish and of pollution of the river and risk of stock poisoning has to be considered.

“Thtis treatment would not completely eradicate the sandflies as DDT has little or no effect on eggs and pupae; tihe treatment would (phobably have to be repeated every four to six weeks. “We hope to be able to give you definite recommendations for treating rivers when we have done some experimental work to test dosages and methods of application. « Abating the Nuisance “In so far as abating the sandfly nuisance in the Government grounds is concerned. I would recommend that the interior walls of those open bathhouses in wljich the sandflies are troublesome should be treated with a 5 per cent. DDT solution in kerosene. This should be applied sufficient to wet the walls and leave a deposit but not sufficient to cause run off of the liquid

—approximately one gallon per 1000 square feet of wall surface. The residual effect should last at least two or three months. A wettable DDT powder (50 per cent, p.p.i.) could be used in the same way at strengths up to lOlbs. per 100 gallons of water. “When sandflies are especially bad in the Government grounds it would be worth while experimenting witji a spray of say 51bs. of 50 per cent, p.p.i. wettaible DDT powder in 100 gallons of water applied to lawns, shrubs and trees around the areas where people congregate. Fifty per cent. DDT wettable powder costs about 8/- a lb.”

The chamber decided that information contained in the letter be referred to the Te Aroha Borough Council and to the manager of the Te Aroha branch, Tourist Department.