ERADICATION OF WEEDS

Hawke's Bay Tribune, Volume XVII, 19 November 1927, Page 12

ERADICATION OF WEEDS

BY INSECT PESTS. INTRODUCTION CRITICISED. English insects from the Rothcmfw The policy of the New Zealand Government in introducing armies of English insects from the Rothamstead Institute for the purpose of checking weeds and brambles has been criticised by English entomologists (says the Parliamentary correspondent of the Christchurch “Sun”), and the suggestion has been made that these importations would turn out to be enemies rather than the saviours that were hoped for. Assurance is given b- the Depaj* ment of Scientific and Industrial Research, however, that the tests that are being carried out at present with parasitic insects as a means of des troying noxious weeds are so elaborate that no releases will be made till the exact ramifications of the insects are ascertained, and the extent of their habits made certain. A noted English entomologist. Mr Ernest Crabbe, Bay's that his experience has shown that Nature is recalcitrant ; she kicks badly when her own arrangements are interfered with. Botanists, he suggests, will smile at such a naive proposal as ridding the country of blackberry with a caterpillar parasite, his remedy being ruthless eradication by human beings. Greajt is the faith of the scientist in New Zealand, he adds, if he believes (hat gorse-weevils will confine their activities to gorse, and leave alone other plants when gorse is not available. The weevil he classes as the most cosmopolitan and omnivorous of all insects, and his belief is that as soon as a brood of them have smelled New Zeeland air. they will soon find something other than gorse to feed on. He warns the New Zealand Government of these insects

Experiments with this class of pest cradicator are not being taken lightly by the scientists in the Dominion, however, and the work that is Being on at the Cawthron Institute with parasites to attack the blackberry, gorse, ragwort, and other noxious weeds, is being done with meticulous care and with methodical precaution against far reaching mistakes. Great hopes are entertained for the effective use of the insect enemy of the blackberry and several consignments of specimens have been imported, while others are coming to hand periodically. It is not likely that anv release will be made before 12 months or two years hence, however, as the experimental field is so wide and the New Zealand plants likely to attract the appetite of the insects are so varied. Dr. R. J. Tillyard’s faith in the ultimate success of these experiments is unbounded, and his operations at, the Cawthron Institute are progressing with relentless precision toward the eventual destruction of the black berrv pest. Earlier results are anticipated in the gorse eradication, however, and it is expected that early next year the weevil with which experiments have been made v»ill be released to pursue its ramifications upon the fastspreading plant. Detailed starvation tests have been carried out with this insect to ascertain its gastronomic desire s on plants allied with gorse and members of the gorse family, and to see whether would die rather than attack plants other than gorse. In many instances it has passed this test, and the re suits are generally regarded as satisfactory. Far from being warned oft —as suggested by English entomologists—the New Zealand authorities are going ahead with the gorse weevil experiment, in the hope of preventing the spread of the plants already existing rather than of killing them. In this way will gorse hedges be preserved, but the seed will not be allowed to spread. Attacks are being made upon earwigs. as well, but these experiments have not as yet come under the Department of Scientific and' Industrial Research. It is learned, however, that this department might be prepared to undertake control of the work if co-ordination with the fruitgrowers is assured. Infected earwigs are being imported to attack the earwig pests already existing in the orchards of New Zealand In their operations with plant pests the authorities claim that they are not upsetting the balance of Nature, but are endeavouring to restore the balance, which has been upset by the introduction and spread of the plants that are now causing so much damage and incurring so much loss throughout the country.