ORCHARD PESTS

Dominion, Volume 21, Issue 84, 7 January 1928, Page 12

ORCHARD PESTS

PARASITES AND SPRAYING A SCIENTIST’S ADVICE In a lecture entitled "Some Insect Friends of the Gardener,” illustrated by lantern slides, which Mr. D. Miller, M.Sc., Government Entomologist, delivered before the Nurserymen’s Association on Thursday, the lecturer stressed the fact that, just as life was a constant struggle between men, so the career of the insect was a struggle against rivals. Insects were responsible for a great annual loss, especially in an agricultural country such as New Zealand. Pear Midge. One of the most important pests was the pear midge from Europe, where it was not a bad pest, and its natural enemies were consequently unknown. The midge laid its eggs in the unfolded pear leaf, which curled up, died, and fell to the ground, where a little grub furrowed. It had a life circle of a month. Research had revealed a useful insect called the platigaster, which destroyed the midge. These platigasters were being brought into New Zealand and distributed, and the orchards where they were at work were now showing a full crop of leaves. Mealy Bug. The mealy bug, which sucked the sap from plants, was now being attacked by aphids from California and Australia. The cabbage aphis, and others, could be attacked by “black leaf 40,” or kerosene emulsion. A small wasp-like insect laid its eggs in the body of the aphis, but, unfortunately, a third insect also laid its eggs in those of the wasp. Ladybirds are the aphis, but an enemy in its turn attacked them. The hoverfly laid eggs among the aphids, and the hatched grub (headless and blind) devoured many aphids. Giant Horntail. The giant liorntail pest on pine trees attacked only weakly trees, boring holes in the tree trunk. The hatching grub enlarged the bole. In Europe this pest was attacked by parasites, including one with an enormously long ovipositor, with which it laid eggs in the embedded grub. This helpful insect was, however, yet to be introduced. “Parasites, however,” added' Mr. Miller, “are only a partial aid. Spraying is still essential in orchard practice.”