INSECT PESTS OF THE EMPIRE.

Hauraki Plains Gazette, Volume XXXVIII, Issue 5209, 28 November 1927, Page 4

INSECT PESTS OF THE EMPIRE.

INVESTIGATIONS BY SCIENTISTS.

WORK AT THE “PARASITE ZOO.”

“At Farnham Royal, a pleasant, oldworld village in the leafy recesses of Buckinghamshire, scientists are at

work upon one of the most, serious and baffling problems of the British Empire. A typical English country mansion, with picturesque grounds extending to about seven acres, forms the scene of their operations. Here, in what has been popularly termed a ‘Parasite Zoo,” they are endeavouring to provide new and more effective means to enable the farmer, the forester, and the cattle rearer of the far-off Dominions to combat the innumerable pests that, work havoc among crops and animals, and not only impoverish the owners but cause losses which, indirectly, add to the cost of our food and timber.

“The extent of the damage done by these pests may be generally indicated by stating that it is estimated that not less than a tenth of the world’s crops raised annually is eaten by insects,” says a writer in the Times Trade and Engineering Supplement. “If we take the tropics alone the figure must be increased to a fifth, and it should be borne in mind that nearly half the British Empire lies within the Tropical Zone Sudh enormous depredations seem difficult to comprehend, yet the difficulty will be lessened if we remember that! in Great Britain itself, where the problem is less serious than in some countries abroad, the yearly loss caused by pests is estimated at £30,000,000. “Canada has to face yearly a loss of £20,000,000 due to field crop pests, and, in addition, between 1914 and I£2l, the spruce bud worm did damage to the extent of £7,000,000' among spruce; and fir trees. Australia loses every year sheep worth £2,000,000' through the ravages of the blowfly, while the cane grub takes toll of sugar cane in Queensland to the extenti of £lOO,OOO.

“Enormous losses are caused in South Africa by the codlin moth, which infests 20* per cent, of apples in normal years and 4'Q per cent. in light crop years. . In Egypt the pink boll-worm caused damage in 1921 amounting to £10,090,000. while in tropical America, north of the equator (including the West Indies), the damaged onq every year by sugar-cane moth borers reaches a total of £2,000,000.

“These rough figures will convey an idea of the gravity of the problem before scientists.

“At present farmers and others in the Dominions - rely chiefly upon chemical means of fighting the great army of pests. Spraying is resorted to on a large scale, but it is by no means a perfect mesthod, and there are certain cropa to which it is impossible to apply this treatment. In recent years it has become more and more clear that thej only satisfactory method is that of biological control, which, in a word, means going back to the lesson of Nature itself and supply to the countries which are pestridden the, parasites whose absence has given rise to the problem. “Operations at Farnham Royal began recently under the direction of Dr. Guy Marshall and Dr. Neave, of the Imperial Bureau of Entomology, ann though they are not yet fully developed a good deal has been done. In a great number of cases the parasites of the various pests are well known, and the task at the new' ‘Zoo’ is merely to breed and export them. “One uses the word ‘merely,’ but it is not to be supposed that all is simplicity itself, for t|her.e are many difficulties, not least of which is the danger of sending out to the Dominions parasites which are not free of hyper-parasites. The latter would, of course, gradually negative everything that had been done. It is also of the utmost importance to export only those parasites which will confine themselves to the pest to be eradicated ; otherwise the Dominions would rid themselves pf one problem only to be faced by another equally or more serious.

“The, greatest care, therefore, has to be taken at every stage of the work at Farnham Royal. The breeding of the parasites is carried out in specially constructed insectorieis. These consist of large 'cages framed in teak and covered at} the sides with copper gausej so fine that no insect life can either enter or escape. In order to admit the ultra violet rays of the sun, so beloved by pqsts and parasites alike, the roofs are. of vita glass. “In one of these cages one observes a number of bushes thickly infested with the woolly aphis, which does such enormous damage to fruit trees Here the appropriate parasite has beejn introduced, and it is left to do its work by laying its eggs in the larva of the aphis and 'destroying it. At a, suitable stage twigs containing the chrysalic of the parasite will be detached and sent to tlhej areas abroad where they are needed. “In another cagei the parasite of the scale—an insect that operates on maple and other trees, sucking th© juicei and destroying them —is bejng cultivated. In a third and much larger cage, the wood-borer and the blowfly are being dealt with, “The mansion 'itself has- been turned into a laboratory, in which microscopic and other work is (Done. It is necessary to make sure that the parasites, when collected, are not only free from thejr own natura enemies, but that they are tihe correct species. In some instances every parasite, however minute, has to be; caught and examined under a powerful microscope before being passed as authentic. “That is the outline of what has be<en done up to tihe present at tfiis remarkable ‘Zoo,’ but there is stilt a considerable amount of work Earwigs do an enormous amount of damage in some of the Dominions, and it is intended to begin very soon thq breeding of the parasite which will keep them Jn check. Tjhe codlin

moth, which ruins millions of apples in Australia, New Zealand, Canada, and South Africa, is to be the subject of research.

“The tsefeo-fly, the wheat-stem sawfly, the born-borer, and the lucerne flea are other pests , which are to be taken in hand at the ealiest possible moment. Even when parasites have been bred and collected there is still the problem of successfully transporting them across thousands of miles of ocean and delivering them in their new home at the right period, and under the right conditions —a task requiring much study. “Thus actual results from the labours of the Imperial Bureau must be slow in making themselves evident, but progress is being made as quickly as possible, and there; is little doubt that when the ‘Zco’ is in full operation the pests of the Empire will for the first time be kept under somer thing like effective control, and scores of millions of pounds will he saved annually to trade,”