Page:Popular Science Monthly Volume 45.djvu/699

Rh are much affected by parasites, and neither of which can survive if the cases are plucked in winter and placed away from any trees or shrubs, while under these circumstances the parasites will perfect and escape.

It is quite different with the second method of dealing with beneficial insects which I have mentioned, for here man has an opportunity of doing some very effective work. It is only within comparatively recent years that the importance of this particular phase of the subject has been fully realized. Various more or less successful efforts have also been made, and the transmission from one place to another of certain parasites of the plum curculio; of certain parasites of the common oyster-shell bark-louse of the apple; the successful colonization in France of a certain mite which attacks the grape phylloxera; the efforts to send parasites of plant-lice from Europe to Australia; the introduction into this country of Microgaster glomeratus, a common European parasite of the cabbage worm, and of Entedon epigonus, a common European parasite of the Hessian fly—are matters of record in State and Government publications.

In 1887 and 1888 the now well-kuown importation of Vedalia cardinalis from Australia and New Zealand to California to prey upon Icerya purchasi was successfully carried out. The history of this striking example of the beneficial results that may in exceptional cases flow from intelligent effort in this direction is now sufficiently well known to American economic entomologists, but anticipating that we shall have foreign delegates among us, and that our proceedings will be published more widely than usual, it will perhaps be wise to give the salient historical facts in the case, even at the risk of some repetition of what has been already published.

The fluted scale, otherwise known as the white or cottony-cushion scale (Icerya purchasi Maskell), is one of the largest species of its family, and up to 1883 had done immense injury to the orange groves and to many other trees and shrubs of southern California. From Australia, its original home, it had been imported into New Zealand, South Africa, and California—the evidence pointing to its introduction into California about 1868, and probably upon Acacia latifolia.

In my annual report as United States Entomologist for 1886 will be found a full characterization of the species in all its stages; but the three characteristics which most concern the practical man and which make it one of the most difficult species to contend with are its ability to survive for long periods without food, to thrive upon a great variety of plants, and to move about throughout most of its life.

The injuries of this insect, notwithstanding the efforts to check