over the young twigs, and the weakened tree gradually died.

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