INSECT PESTS

Waipa Post, Volume 32, Issue 1782, 13 July 1926, Page 7

INSECT PESTS

A CHAT TO HORTICULTURISTS

A decidedly interesting chat, illustrated I)3' many lantern slidies, was given by Mr D. Miller, Government entomoligi'st, to members of the Wellington Horticultural '.Society at its annual meeting last week, ion the subject of “Insect Pests of the Garden, and how to 'Control Them ” (reports the Evening Post). It was a mistake to think that all insects were pests, said, Mr Miller; each had, some useful purpose to perform, and insiectls became only when they interfered with man’s agricultural and horticultural products. Since New Zealand was very largely placed under cultivation many of the native insects had turned to man’s products, but only 29 per cent of the pests which worried the gardener and the farmer were natives, and the remaining 71 per cent had 'been introduced in one way or another, mostly from Europe.

Referring !to individual pests, Mr Miller said that the best means of control in the case of the well-known grass grub was to ensure stronglygrowing plants, since these were less liable to damage from the grub than weaker plants. A thorough rolling also assisted by compacting the surface, which in areas which were badly attacked became characteristically spongy. Turning up and re-sowing were rejally a waste of time, for that did not kill the grubs. Starlings and sparrows killed many grass grubs, and a natural insect enemy 1 , , the robber fly, both as grub and mature insect, assisted in keeping 'the grub in check. The “subterranean grass grub,” another native, was also dfe■scribed; the. Government was at present carrying out experiments for the' control of this pest, and hoped to be able to announce the selection of a suitable insecticide by next spring. The “ cut-worm ” caterpillar, so called from its habit of nipping off young plants, could be kept under control by the use of poisoned bran (treacle and paris green) and by clean gardening, that was, the removal of weeds and waste growth, and winter killing, these latter means being of very real importance in all gardening and farming. The cut-worm had numerous natural enemies. The wellknown “ magpie ” moth and its grub, “ the woolly bear,” were fairly well controlled by the use of arsenate of lead, commencing in the early spring. A poisoned! spray would not kill the cabbage aphis, but a contact spray was effective. Similarly the “thrips” pest -was best controlled by a nicotine contact sprayt Neither poison nor contact spray was effective against the “ mealy bug,” but the Government was assisting in its "control by the breeding and. release of a particular ladybird. 'Eel-worm, which attacked bulbs, tomatoes, and many other plants, was difficult of control, and really the only successful method was by means of steam sterilisation, or by hot water, up to about 140 degrees, where only the small quantities of soil were being dealt wit'll'.