INSECT PESTS

Evening Post, Volume CXVI, Issue 135, 5 December 1933, Page 10

INSECT PESTS

MOSQUITO CONTROL

EXPERIMENTS BEING MADE

Speaking at the Eotary Club luncheon today, Mr. W. J. Phillipps, of the Dominion Museum, staff who has devoted a considerable amount of study to mosquito life, gave sonic interesting facts in regard to the mosquito pest and its control. Tho mild winter which had just passed had been responsible for an unusually largo number of insects of all kinds being seen in New Zealand this summer, said Mr. Phillipps. All over tho North Island, particularly in places where swampy areas and standing water pools were common, mosquitoes had been found in larger numbers than for some years past. The adult mosquito lays anything up to 300 eggs at the- edge of a pool. These eggs hatch in anything from three days to a week or more. The larva which emerges is a wriggling animal very sensitive to light and shade. In good surroundings at an even temperature it hatches in a little over a week into a pupa; but if the water is exposed to frost may easily bo killed by cold nights, or if tho temperature of the water is lowered to a certain extent it can live on for many weeks, perhaps months in a more or less comatose condition. The pupal or resting stage is a comma shaped animal, in which the breathing organs are situated on the head. This hatches in from two to five days into an adult mosquito. Thus in a little over a fortnight an adult mosquito may be the mother of something near 300 young. It is only tho female mosquito which bites. Man, he said, is a successful animal in his sphere of activity; but so is a mosquito. Now man and mosquito are in conflict, and man must win. Several diseases are caused by mosquitoes, and it would como as a surprise to many to know that' there were in the south of England three species of mosquito capable of carrying malaria and transmitting it to human beings. These mosquitoes (Anopheles) were not found in New Zealand; .but we must keep constant watch in order to see that they do not get here. The direct route to Panama opened up possibilities of other species getting here, but the Health Department keeps careful supervision over all boats coming to New Zealand ports. The best guarantee, remarked tho speaker, that no overseas mosquitoes could establish themselves in New Zealand was the absence of suitable breeding places; and, once we cleaned up all possible places where mosquitoes could breed, the future was assured. It was not always practicable, however, to eliminate water areas, so control by natural means in place of the old idea of using oil to kill the larvae was gradually being used. Fish and water birds are used to cat the larvae in various parts of the world, and experiments in using these are being tried in various parts of New Zealand. Water snails are being also used to purify tho water by eating up decaying life and the minute organisms on which the larvae live.