WARE MOSQUITOES!

Sun (Auckland), Volume III, Issue 886, 1 February 1930, Page 5

WARE MOSQUITOES!

NO STAGNANT WATERNO PESTS HOW TO DESTROY THEM (Contributed by the .Department of Health.) Mosquitoes, besides being in some instances the means of conveying disease from one human being to another, cause great annoyance by their bites. There are four distinct stages—(l) The female lays one hundred or more eggs in one batch. The eggs are minute blackish bodies usually laid ou the surface of still or stagnant water. The common rain barrel type, and also many others, glue their eggs into rafts which look like flakes of soot. The burden of the cry of the female mosquito is “give us blood.” Before it can lay eggs a meal of blood is a necessity. (2) In one to three days the eggs hatch into larvae. These are the “wrigglers” from their habit of wriggling through water with quick jerky movements. They must keep coming to the surface to breathe. This is effected through a breathing tube located in the tail. Their food consists of minute particles of vegetable or animal matter. (3) In about a week, if the weather is warm, the wriggler casts its skin and turns into a comma-shaped body called the “pupa” or “nymph.” The pupa takes no food, but, like the wriggler, comes to the surface to breathe. Its breathing organs this time are situated close to the head. (4) After two to live more days the skins of the pupa split open and the winger mosquitoes emerge to the surface of the water and fly away. Male mosquitoes are vegetarians; it is only the female that bites. When she bites she in- ! jects into the victim a fluid from her salivary glands through a tube-like arrangement. 11l this fluid are sometimes the organisms which produce malaria. BREEDING PLACES No 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 fact, anywhere where water is allowed to stand. In New Zealand the larva,e have been found in rain water, in holes in 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 coastline in semi-saline or brackish pools of water. Large sheets of water, lagoons and rivers are unsuitable, although they may be found in adjoining pot-holes and puddles. A certain number of adults survive the winter. In Auckland adults, larvae and pupae have been found in wet cellars in mid-winter. Bushes afford shelter, but' not breeding grounds. PREVENTIVE MEASURES The control of tlie mosquito is largely the control of breeding places. Certain natural enemies are of service, fish are very effective, and the margins of pools and streams should be kept free of vegetation to allow the fish access. Ornamental ponds may he stocked with goldfish or minnows. Dragonflies and water beetles are also very useful. Anything which collects water should be dealt with. Unnecessary scrub may be cleared, but it 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, one teaspoonful to the gallon of water, or enough to make the water milky when stirred. (2) Coal tar, one pint; turpentine, one pint; soft soap, one ounce, water to make up to two gallons. This will treat 300 gallons of water. (3) Add copper sulphate to the water to be treated in the proportion of one part to 5,000 of water.

Stored water supplies may be screened (18 meshes to the inch), closed in, or a layer of sawdust spread upon the surface. Against the egg stage “race suicide” measures may be used. Hang cigarette tins balffilled with water, or, better still, hay infusion, under the branches of trees. The eggs are laid in these. Empty the tins every 48 hours into a saucepan and boil the water to destroy the eggs.

The adult mosquito dislikes smoke. The burning of pyrethrum powder, 31b to the 1,000 cubic feet in a closed room, is useful. This stupifies 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, and as high as possible. Remember, however, the slogan: “No water, no mosquitoes.”