INSECT PESTS

Evening Post, Volume CVIII, Issue 99, 23 October 1924, Page 7

INSECT PESTS

AND THEIR NATURAL ENEMIES

PROTECTING FRUIT AND GUM

TREES

It cannot be denied that Mother Nature has visited many and various clasSei of insect pests upon the world, but in her always wonderful way, she has never forgotten to provide some means wher«by this scourge might be overcome, or at least kept within reasonable bounds of control.

One particular variety of. parasite ;which haa caused a little damage to gum trees in .the northern districts is th« ."scale" (Ericoccus Coriaceus). This pest confines its attention particularly to eucalyptus trees, from which ivsucks the sap, and its ravages have been very evident f.rom the district west of Wanganui to the East Coast and from. Taihape to Longburn. .. As a means of combating the parasites, the Dominion Entomologist (Mr.: David Miller) obtained from Australia, the home of.the " scale," consignments, of a variety of black ladybird (Rhizobius Veneralia), a natural enemy of the pest, which hi liberated in the affected areas.

Quite satisfactory results were ob: tamed, but great difficulty is still being found in controlling the " scale," because of its ability to spread itself by means of the wind, which carries it from one tree to another. There is, no means of preventing this very: simple means of transit; and in consequence the -'scale" is able to find new.pastures at any time. The female "scale" is not able to fly, .but, although the male has useful wings, it does not do,any direct damage. When speaking to a " Post" reporter to-day. Ml. Miller stated that, although the ladybird had done good work in many parts, there were. some places in which the "scale" had become beyond control. The reason for' this was that a little red mite was attacking the eggs of the ladybird and sucking them dry. This, of course, prevented the ladybird breeding in sufficient numbers to combat tho "scale." On the average, however, th« results were reasonably good. Publicity was recently given by . th« Department of Agriculture to the danger of specimens of the "ecale" being sent out of the infected areas, and Mr." Miller emphasised this point. The pest might be considerably spread' in this way. - There is another natural enemy of the ?'scale " which in Australia, the native land of both insects, attacks the parasite. With the assistance of the Government Entomologist in" Sydney, arrangement! are being made for consignments of this enemy of the- gum tree pest to b« sent across to New Zealand. It is the larva of a moth, and when in the caterpillar {stage it feeds on 'the "scale." Last autumn Mr.' Miller obtained some of these larva from Tasmania, and liberated them in the Palmerston North district, but as yet he has not been able to ascertain if they have succeeded in establishing themselves However, something definite as to their activities should be available in the n«ar future, or at least after the new consignments have been liberated. A DESPOILER OF APPLES. Another pest that" has become quite a, problem, in th» New Zealand orchard districts is the "mealy bug,".,an insect of' quite considerable size, which confines its attention to apples. With a view to lighting this parasite "-another form: of Australian ladybird .is .being bred by Mr. Miller in the Biological Laboratory at Kelburn. Quantities of the bug have been aeenred and they are fed on the sprouts of .potatoes, a diet which they appear to particularly appreciate. When 11) ey have attained a reasonable size they are then used as food for the ladybirds, which are being bred extensively for the purpose of liberation in the orchard districts. Some were given their freedom last summer, but the results of their work will not be evident for som« time yet. Mr. Miller has made arrangements to secure consignments of two I other natural enemies of the "mealy bug' from California, one of them a ladybird and the other a chalcid. In this great American orchard land, thes« insects haye been bred extunsively, and their services have been employed with very satisfactory results in-the protection of the apple.