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Page:Popular Science Monthly Volume 72.djvu/369

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365
INSECTS INJURIOUS TO AGRICULTURE

In 1894, at the opposite extremity of the United States, in the State of Florida, a new invasion of Icerya purchasi was produced, and the scale insect was introduced, this time under conditions which show very well the risks attending such attempts to acclimatize useful insects when they are made by incompetent persons. A nurseryman in Hillsboro county, Florida, having heard of the extraordinary services rendered by the Australian ladybird, being ignorant of the fact that this insect will not attack other insects than Icerya, sent to California for Novius cardinalis to fight the Aspidiotus, or other scale insects, feeding upon their plants. The Novius was naturally sent with some Iceryas which would serve as food for it on the journey, and they were all placed together by the nurseryman upon the trees which he desired to protect. No one knows what became of the Novius, but the Icerya multiplied and was not slow in covering the trees upon which it had been placed. Radical measures were almost immediately taken; all the trees attacked were burned; and for four years nothing was heard of the insect. It was believed to have been entirely exterminated, but in 1898 the presence of specimens of Icerya was discovered. The formidable scale insect was found at this time at several points near the locality where it had been first imported, and it had invaded one or two orange groves. It was necessary to give up all hope of exterminating the species, and an immediate effort was made to introduce Novius cardinalis.

Mr. Gossard, state entomologist of Florida, and Mr. Al. Craw, entomologist of the State Board of Horticulture of California, directed the work. The Novius was at first colonized with success in two of the infested orchards, and in 1900 had become sufficiently well established to enable them to distribute it in good number in infested localities. It seems to be certain that Icerya finds in Florida conditions less favorable to its development than in California. It has been stated that it is attacked there by a fungous disease. In any event it can not be doubted that with the assistance of Novius cardinalis, it will never play in Florida the injurious rôle which it has played on the Pacific coast.

America is not the only country which has suffered from the introduction of Icerya purchasi. This insect has been imported, or was imported at almost the same time, into South Africa; and more recently it has made its appearance in the Sandwich Islands, in Portugal and in Italy. Novius cardinalis has in these cases been sent for, and the success has been as complete as that obtained in California.[1] The history of these successive invasions and of the efforts which have been made to combat them conveys useful instruction and is worthy of our attention.

Icerya purchasi and Novius cardinalis at the Cape.—About 1890,

  1. Novius cardinalis has also rendered great service against Icerya in New Zealand.