In this way orchard after orchard of oranges, worth a thousand dollars or more an acre, was utterly destroyed; the best fruit-growing sections of the State were invaded, and ruin stared many a fruit-grower in the face. This spread of the pest was gradual, extending through a series of years, and not until 1886 did it become so serious a matter as to attract national attention.
In this year an investigation was begun by the late Professor C. V. Riley, the Government entomologist then connected with the Department of Agriculture at Washington. He sent two agents to California, both of whom immediately began to study the problem of remedies. In 1887 he visited California himself, and during that year published an elaborate report giving the results of the work up to that point. The complete life-history of the insect had been worked out, and a number of washes had been discovered which could be applied to the trees in the form of a spray, and which would kill a large proportion of the pests at a comparatively small expense. But it was soon found that the average fruit-grower would not take the trouble to spray his trees, largely from the fact that he had experimented for some years with inferior washes and quack nostrums, and from lack of success had become disgusted with the whole idea of using liquid compounds. Something easier, something more radical was necessary in his disheartened condition.
Meantime, after much sifting of evidence and much correspondence with naturalists in many parts of the world, Professor Riley had decided that the white scale was a native of Australia, and had been first brought over to California accidentally upon Australian plants. In the same way it was found to have reached South Africa and New Zealand, in both of which colonies it had greatly increased, and had become just such a pest as it is in California. In Australia, however, its native home, it did not seem to be abundant, and was not known as a pest—a somewhat surprising state of affairs, which put the entomologist on the track of the results which proved of such great value to California. He reasoned that, in his native home, with the same food plants upon which it flourished abroad in such great abundance, it would undoubtedly do the same damage that it does in South Africa, New Zealand, and California, if there were not in Australia some natural enemy, probable some insect parasite or predatory beetle, which killed it off. It became therefore important to send a trained man to Australia to investigate this promising line.
Vedalia, or
Australian
Ladybird
After many difficulties in arranging preliminaries relating to the payment of expenses (in which finally the Department of State kindly assisted), one of Professor Riley's assistants, a young German named Albert Koebele, who had been with him for a number of years, sailed for Australia in August, 1888. Koebele was a skilled collector and an admirable man for the purpose. He at once found that Professor Riley's supposition was correct: there existed in Australia small flies which laid their eggs in the white scales, and these eggs hatched into grubs which devoured the pests. He also found a remarkable little ladybird, a small, reddish-brown convex beetle, which breeds with marvellous rapidity and which, with voracious appetite, and at the same time with discriminating taste, devours scale after scale, but eats fluted scales only—does not attack other insects. This beneficial creature, now known as the Australian ladybird, or the Vedalia, Mr. Koebele at once began to collect in large numbers, together with several other insects found doing the same work. He packed many hundreds of living specimens of the ladybird, with plenty of food, in tin boxes, and had them placed on ice in the ice-box of the steamer at Sydney; they were carried carefully to California, where they were liberated upon orange trees at Los Angeles.
These sendings were repeated for several months, and Mr. Koebele, on his return in April, 1889, brought with him many more living specimens which he had collected on his way home in New Zealand, where the same Vedalia had been accidentally introduced a year or so before.
Larvæ of Vedalia
eating White Scale
The result more than justified the most sanguine expectations. The ladybirds reached Los Angeles alive, and, with appetites sharpened by their long ocean voyage, immediately fell upon the devoted scales and devoured them one after another almost without rest. Their hunger temporarily satisfied, they began to lay eggs. These eggs hatched in a few days into active grub-like creatures—the larvæ of the beetles—and these grubs proved as voracious as their parents. They devoured the scales right and left, and in less than a month transformed once more to beetles.