INSECT PESTS.

Hawera Star, Volume XLVIII, 1 November 1924, Page 15

INSECT PESTS.

AND THEIR NATURAL ENEMIES. PROTECTING FRUIT AND GUM TREES. It cannot be denied that Mother Nature has visited many and various classes of insect pests upon the world, but, in her always wonderful way, she has never forgotten to provide some means whereby this scourge might be overcome, or at least kept within reasonable bounds of control. One particular variety of parasite which has caused a little damage to giim trees in the northern districts is the “scale” (Eric-oeeus Coriaeeus). This pest confines its attention particularly to eucalyptus trees, from which it sucks the sap, and its ravages have been very evident from the district west 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 iof the pest, which he liberated in the affected areas. Quite satisfactory results were obtained, 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 110 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 recently, Mr Miller stated that, although the ladybird had done good work iii many parts, there were some places in which the “scale” had. become beyond control. The reason for this was that a little red miti was attacking the eggs of the ladybird and sucking them dry. This, of course, prevented the ladybird breeding in sufficient numbers to combat the “scale.’On the average, however, the results were reasonably good. Publicity was recently given by the Department of Agriculture to the danger of specimens of the “scale” 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” whieh in, Australia, the native land of both insects, attacks the parasite-. With the assistance of the Government Entomologist in Sydney, arrangements are being made for consignments of this enemy of the gum tree pest to be sent across to New Zealand. It is the larvae of a moth, and when in the caterpillar Stage it feeds on the “scale.” Last autumn Mr Miller obtained some of these larvae from Tasmania, and liberated them in the Palmerston North district, but as ye.t 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 hear future, of at least after the new consignments have been liberated. v A DESPOILER OF APPLES. Another pest that has become quite a problem ih the New Zealand orchard districts is the “riiealy bug,,” an insect of quite considerable size, which confines its attention to apples. With a view to fighting 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 secured and they are fed ton the sprouts of potatoes, a diet which the;- appear to particularly appreciate. When the;/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 fr.eedom last summer, but the results of tlieir work will not be evident for some time yet. Mr Miller has made arrangements to secure consignments of two other natural enemies of the “mealy bug” from California, one of them a ladybird and the other a chflleid. In this great American orchard land these insects have been bred extensively, and their services have been employed with very satisfactory results in the protection of the apple.