INSECT PESTS.

Hauraki Plains Gazette, Volume XXXVI, Issue 4900, 6 November 1925, Page 4

INSECT PESTS.

THE CONQUEST OF DISEASE

SCIENTIFIC STEPS TAKEN.

Sir Ronald Ross recently peiTormed the opening ceremony of the new building .for the Mosquito Control Institute at Hayling Island. Five years ago a very serious plague of mosquitoes- in South Hampshiic led ti° concerted measures for control by the draining of stagnant water and other methods, and one result was the establishment of the institute, with Dr. J. F. Marshall as its director. The efforts undertaken to .abate the plague have been very successful, and recently Dr. Marshall described the work of the institute in a paper read before the British Association, at Southampton. .When the new building was opened by Sir Ronald Ross many members of the British Association were present. In an interview with an “Observer” representative Sir Ronald Ross said •

"Our work for the general extermination of insect pests is designed chiefly for the protection of cities, and towns. • We cannot expect—indeed, there is' no need—to drive mosquitoes and the like out of jungles and marshy tracts away from civilisation; The area of flight of noxious insects has been shown by repeated tests to be 'Strictly limited, extending to a very few miles at the most. “From a purely economic point oi view, quite apart froni humanitarian grounds, it would be far cheapen for Governments .and local public bodies, as well as individuals, to contribute to preventive and research, work, such as ip going 'on in Hayling Island and elsewhere. The amount of sickness and death averted- would be out of all proportion to the cost. “It would be quite feasible for a rich country to put down a large sum of money for dealing with ..these insect pests rather than to spend a Hundred times as much—-.and this is done readily enough—for killing off a few human adversaries. ■ Why, the money spent on a single dreadnought would ■simply work’ wonders if applied in this way.”

piSEASE CARRIERS. Insects were first proved to be carriers of disease in the second half of the last century. The late Sir Patrick Manson showed that ax tropical parasite of man, called flaria, was conveyed by a species of Culex mosquito. . This was a very important discovery, as the parasite causes the terrible disease known as elephantitis in many tropical countries. In the ’nineties some American observers found .that Texas cattle fever is carried by a tick, and Sir David Bruce, late president 1 of the British Association, showed that the widespread Nagana disease of African cattle was due to trypanasmes carired by the tsetse fly, and inoculated by its bite. lBBO Dr. A. Laveran discovered that what is, perhaps, the nrpst important of all human diseases, namely, malarial fever, is caused by .a little parasite in the blood of man.’ This disease had always been connected, from the time of the ancient Romans,

and possibly of the dreeks, with stagnant water on the ground, and up to 1895 every medical scientist, including Dr. Manson, suispected that it might be carried in some way by mosquitoes. This was proved to be the case by Sir Ronal.d Ross between the years 1895 and 1899, as the result of a long series of investigations carried out; in India. His conclusion was varifled and extended—in Italy chiefly by Dr. A. Bignami, in Africa by Drs. Daniels,, Stephens, and Christophers, and elsewhere by other enthusiastic workers too numerous to mention. Largely in consequence of this discovery Schools of Tropical Medicine were founded in 1899 at Liverpool .and in London foi’ the purpose of teaching the new knowledge and promoting further studies.

MOSQUITOES AND YELLOW FEVER. Early in 1901 the American doctors Reed, Carroll, Lazear, and Agramonte verified the previous hypothesis of Dr. C. Finlay, of Havana, that mosquitoes also carry yellow fever. Malaria is! carried by variouis species of the genus of mosquitoes called anopheles, whereas yellow fever is carried by the Stegomyia ; but the breeding habits of all these ipsects, beingdifferent, require very careful investigation.

Sir Ronald Ross carried, out his work not for. entomological, but for sanitary reasons. From 1899 onwards •lie paid visits to nine different countries or colonies with a, view to urging the reduction of malaria-bearing mosquitoes in them : and other methods of prevention, such as 1 the use of mosquito nets and —as regards mallaria —of quinine, were advocated by him and by others. But hithough this matter has now been pl.aced fully and frequently before the public for more than a quarter of a century, the progress made in response to scientific advice continues to be very slow. ‘ Almost the first actual proof of malaria being affected by “mosquito reduction”—now often hailed ’"mosquito control” —was given in the • French town of Ismailia, on the Suez Canal, in 1903, on the advice of Sir Ronald Ross and Sir William Macgregor, Governor of Lagos, who accompanied him' to that town, which was entirely rid of the disease within a few months. . ' • ■ PANAMA MADE HEALTHY. The Americans had meanwhile already started mosquito control in Havana, against both yellow fever and malaria, as was first recommended by Sir Ronald, Ross in 1899. In .1904' Americans began the construction of the . Panama Canal, and by means of this new system of phophylaxis they were able to complete it without the immense loss of life previously experienced by the French from yellow fever and malaria. Colonel Gorges was- the head of the sanitary department in both Havana and Panama, and his admirable methods are famous throughout the wold.

British attempts at the control of malaria have been making headway only very slowly. This may be due to the fact that such efforts have been local for the greater part. Special mention must be made in speaking of British efforts of the work of Dr. Clark at Hong Kong and of Sir Malcolm Watson and others in the Federated Malay States: jAT HAYLING ISLAND.

Dr. Marshall has been assisted in his research work during the last five years by/ Sir Richard Gregory (editor of “Nature”) and other residents. They have also been greatly helped by Colonel S. P. James, of the Ministry of Health, ■‘and Mr F. W. Edwards, of the British Museum. The results have been remarkably good. The Ministry of Health, the Havana. Rural District Council, and many

local, residents have subscribed towards the cost of the somewhat extensive measures required. Another centre doing a cognate work is the Ross Institute and Hospital for Tropical Diseases, Putney Heath. Recently founded by Sir William Simpson and Dr. Aldo - Castellani, with Sir Charles McLeod, Bart., as chairman, it will be opened almost immediately. Sir Ronald Ross is. the Director-in-Chief of this institute, which lia.s been founded by public subscription, aided by grants from some tropical Governments.