War in the Air

Sun (Auckland), Volume II, Issue 557, 9 January 1929, Page 10

War in the Air

WHEN MOSQUITOS MOBILISE How to Fight the Invader IE Auckland is to be successful in its battle against that winged enemy of health, the mosquito, the campaigners must have the co-operation of every resident. This warning was issued this morning by Mr. Gilbert Archey, of the Mosquito Investigation Committee, who said that the backyards of city homes had been found to be breeding places.

SSISTED by special grants, the committee lias been conducting its mosquito war in the province for the past two years. Armed with nets and collecting pots, Mr. D. H. Graham, the research officer, has explored the city and outlying districts, with the result that seven different species have been identified in Auckland. Of these, two in particular are familiar to residents. Tiist is the small night-biting mosquito, author of that distressing buzzing sound that drives sleep from many a bedroom. His close ally is the slightly larger, white-spotted mosquito, which bites during the day. The daylight biter, together with another species in North Auckland, has been identified as be onging to the same genus as the yellow fever mosquito, Aedes Calopus, so it seems clear that *^ ew Zealand conditions might favour the yellow fever carrier itself. a ' D i SC V ssi P, s the announcement from Australia that malarial mosquitoes had been found to bo existing in the Leeton irrigation areas in enormous quantities, Mr. Archey said that, as far as possible, a thorough investigation had been carried out in Auckland, and the committee was now seeking the co-operation of the citizens. DOUBLE PROBLEM A double problem had to be faced: I 2 Q Swarding against the introduction ot tlie yellow fever mosquito, and the investigation of the possibility of the Aew Zealand species carrying the disease from people who may be sufferers. To breed successfully it was necessary for the mosquito to have water, and the large permanent areas of water were usually supplied with controlling agents such as fish, frogs and other insects. But the mosquitoes that worried city residents bred, for the most part, in household yards and refuse; in odd tins, disused or neglected wash tubs, gutter spoutings and various drainage traps. To combat breeding in these places residents must undertake the task of oiling and the clearing of long grass and refuse. BREEDING-PLACES Xo body of water is too small for a mosquito nursery. They breed in puddles by the roadside; in old tins bottles, fire-buckets, choked roof gutters, flower-pots, tubs, etc.; in cesspools, drainage sumps, swamps, pools slow-flowing and weedy streams, river estuaries; in fa.ct, an v where where water is allowed to stand. In New Zealand the larvae have been found in rain water, in holes jn the trunks of trees, and dead treeferns, and at the bases of the leaves of broad-leaf plants: in crevasses and depressions of volcanic areas, and along the coast-line in semi-saline or P i° o,S ° f ' vater - Large sheets of vater. lagoons, and rivers are unsuitable. although they may be found m adjoining potholes and puddles A certain number of adults survive

the winter. In Auckland City adults, larvae, and pupae have been found in wet cellars in mid-winter. Bushes, etc., afford shelter but not breeding grounds. The Department of Health advocates that anything which collects water should be dealt with. Old tins, bottles, etc., should be removed and buried; spouting must be cleared and receptacles emptied at least once a week and allowed to become dry before refilling. Much may be done by the draining and abolition of swamps, filling in of ponds and depressions, and the straightening and cleaning of streams and ditches, or by the use of drainpipes. Unnecessary scrub may be cleared, but is useless if water remains. Where water cannot be removed, such should be sprayed weekly with kerosene. The water must be covered with a complete layer of oil, two tablespoonfuls should cover 15 square feet of surface. A good spray mixture is kerosene 60 parts, fuel oil 40 parts. These oil films kill the larvae by preventing breathing. The addition of a little castor oil to the kerosene gives a better film. Wind is apt to destroy the film. The following larvicides are effective: (1) Commercial cyllin, i teaspoonful to the gallon of water, or enough to make the water milky when stirred; (2) coal tar 1 pint, turpentine 1 pint, soft soap loz, water rna-ke up to two gallons; this will treat three hundred gallons of water; (3) add copper sulphate to the water to be treated in the proportion of one part to five thousand of water. SCREENING WATER Stored water supplies may be screened (IS mashes to the ~ inch), closed in, or a layer of sawdust spread upon the surface. Against the egg stage “race suicide” measures mav be used. Hang cgiarette tins half-filled with water, or. better still, hay infusion, under the branches of trees. The eggs are laid in these. Empty the tins every 43 hours into a saucepan, and boil the w'ater to destroy the eggs. DISLIKES SMOKE The adult mosquito dislikes smoke—flat cakes of dried cowdung, sprinkled with pyrethrum powder and then burnt, may be tried. The burning of pyrethrum powder alone, 31b a 1,000 cubic feet in a closed room, is useful, rhis stupefies the insects, which must be swept up and burnt. Citronella oil will protect the face and hands to some extent. If this stains the clothes, the stain can be removed by oil of turpentine. Healthy sites for houses should be chosen to windward of swamps, etc., and as high as possible. Friar’s balsam allays bites. The sanitary inspectors of the Auckland City Council have tackled the pioblem earnestly, and extensive oiling of street drainage traps has been carried out. The investigation committee has applied for a further grant which has been approved by the New Zealand Institute and is awaiting the sanction of the Minister. The funds are required to further the study of mosquito control, to examine the countrv areas more thoroughly, and search for other species.