{TREE PESTS CHECKED

Dominion, Volume 16, Issue 170, 6 April 1923, Page 9

{TREE PESTS CHECKED

. LADYBIRDS WORK FOR GOVERNMENT.

AND SAVE EUCALYPT PLANTATIONS

In view of the way in which importiecl pests thrive in this favoured land, it is always to record a victory for in its unceasing battle to preserve, the New Zealand forests and crops. Iho worK quietly carried on by the Government Biological Laboratory is little heard of, yet it is one of national importance, and its latest success will bo warmly welcomed by the many people who are planting eucalypts for their own use, while it will safeguard the extensive State plantations from the. extinction threatened by the particular form of scale-blight which attacks A good deal of eucalypt planting had been done in the Marton, Feildmg, and Bulls districts, and the trees, which were making fine growth, wore attacked by the scale-blight. Th’s blight, though well known in the South Island for' 20 years, made its appearance in the above-mentioned districts only some 18 months ago. but its ravages were so extensive that the position was serious. The coccid sucks the Bap out of the trees, attacking the bark, shoots, and branches. At the feame time it exudes a secretion called “honeydew.” which collects on the 'trees, giving them a blackened appearance, so that the disease is thought by many people to be fire-blight. Not the least interesting form of fighting such pests is that of introducing some other insect that preys only on the particular insect it is desired to get rid of. In this case_the attacking insect is a ladybird. Last voir fairly largo consignments of the ladybird were liberated in the plantations near Greatford and Marton. “I have just come down from the district to-day/’ said Mr. D. Miller, the Government entomologist, to a Dominion • representative yesterday, “and I find that the ladybirds have spread surprisingly, and are doing good work. These ladybirds prey only on this particular scale, which both tho beetle, and its grubs attack, and it looks' as though the blight will, be completely eradicated. ’ “In one case a plantation had been so badlv attacked by the blight that it looked as if a fire had run through the trees and .had searched them. So bad-was the infection that-'the trees were given up as dead. Since the introduction 'of the ladybirds the trees are returning to life in a remarkable way, and though the tipw- snoots still have a little of the blight, the ladybirds arc increasing so rapidly that it looks as though they would completely clear up the scale, and the approaching spring should see a great diminution in the nest. We are breeding these ladybirds at the laboratory quite successfully, and largo further consignments-will be liberated. The scale attacks practically all species of eucalypts, Xbui bluegums particularly, especially where they have been attacked by the gall chalcid.”