ENEMIES OF PLANT LIFE.

Otago Witness, Issue 3190, 5 May 1915, Page 10

ENEMIES OF PLANT LIFE.

In general, the insect pests which now and then upset the whole balance of Nature are 'of two kinds —those which nake their home in the plant itself, the plant acting as the unwilling host of the pest, and those other pests which prey upon the plant without. Most of these are true animal life—flies, mites, caterpillars, etc. There are, too, pests o'f another type, vegetable in character, low forms of plant life, fungus in growth—rust, mildew, smut, and the like —diseases rather than pests, which often do immense damage to growing crops. To combat these pests a great deal of scientific work has been done, and thousands of pounds spent. In an interesting Work, written by W. S. Harward, we arc told how, at intervals, the great fruit industry of California has been threatened through the _ ravages of some insect, how the total extinction of a fruit has seemed imminent —that exceptional opportunities, c*n account of ocean communication with foreign countries, led to the introduction of various pests by importation. To quote an example : —-‘‘lt happened one day that a fruitgrower imported a certain kind of lemon tree, which he thought would be an improvement on the local stock; but it proved to be the home of a tiny insect, a scale, very small but capable of marvellously rapid reproduction. Its mission was to destroy triage, blossoms and fruit. The stock was sold’ to others without knowledge that the scale was upon it, and in a comparatively short time the whole citrus fruit industry of Southern California was threatened with extinction. While orange shipment? were not so large then as later on, yet the year before the scale was introduced about 8000 car-loads were shipped. When the scale

got fairly at work, the shipments dropped to 600 oar-loads in a year. Fumigation, washes, rooting-up of orchards, wholesale burnings were useless; nothing availed, for the pest had spread tc all vegetation, and was rapidly turning the country back into the desert from which it had originally been wrested. At this critical juncture help came from an unexpected source. A tiny insect, a beautiful little thing, brilliant red in colour, not more than the sixteenth of an inch in diameter, one of the family of ladybirds, became the salvation of the fruit industry of a great State. The Horticultural Commission of the State learnt that such an insect lived in Australia,, and that where it abounded the scale was in some way held in check. Through the co-operation of the Secretary of State, a few of the eggs of the insect were secured and brought to the United States and hatched out. As quickly as possible the insects were liberated in the infected regions. They seemed to be fully as rapid in their reproductive powers as the scale.. Instantly upon being released near an infected tree the tiny ladybird searched out the scale and began its work of destruction. It would feed on nothing else but the scale. It was Nature’s method of dealing with any factor which threatened to permanently disturb her balance.. The orchards put on new life, and the fruit industry was saved. Millions of dollars’ worth of property owed its existence to the tiny foe of the pest. The Yedalia cardinalis had won the day, and the ravages of the cottony cushion were at an end.