INSECT PESTS

Evening Post, Volume CIII, Issue 141, 17 June 1922, Page 6

INSECT PESTS

THEIR DESTRUCTION BY NATURAL i ENEMIES.

"Insect Pests and their Control," was the subject of an interesting address given by Mr. David Millar, Government Entomologist, before* the delegates attending the Fruitgrowers' Conference.

If we review tho injurious insects occurring m New Zealand," ho said, "it will be found that of the approximate total, fully 71 per cent, is represented by species introduced from other countries. Of these foreign elements, the European is by far the most dominant, ■being approximately 68 per cent, of the total; other elements are Australian, North lAmerican, Pacific Islands, and South African, of which the Australian is the most prominent, though very small in comparison with tho European. The native insects which have become injurious comprise 29 per cent., and, together with the European, arc the most pronounced element. Considering tho distribution of the injurious insectß, the groatest numbers infest orchards for the most part, and are, in consequence, considerably localised, being confined to approximately 2 per cent, of the total area at land under cultivation in the Dominion. Although the orchard pests comprise one of the largest groups, _ the damage caused by them is comparatively little owing to the efficient spraying methods adopted in orchard practice."

In regard to tho matter of controlling orchard pests by means of natural insect enemies, the speaker stated that orchardists must not think that they will be able to lay aside their spraying apparatus as soon as insect parasites are liberated. It is only in comparatively few instances that a parasite- when liberated in the orchards of a new country will establish iteel£ sumciently of its own accord to be of any practical use. In general insect parasites must be looked upon only as auxiliaries in the fight against insect pests until fully established, and not as the main factor of control. With this in view the breeding of beneficial insects on a largo scale for distribution seasonally to areas infested with certain pests had been commenced at the Biological Laboratories, and it was hoped that by so keeping the orchards constantly stocked that the orchardist would be materially aided in his fight against destructive insects. A start in the distribution of beneficial insects had already been made in other directions, for example, with the steelblue ladybird against the destructive gol-den-oak scale, and the wasp parasite of sheep maggot-flies.