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Page:Popular Science Monthly Volume 72.djvu/371

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367
INSECTS INJURIOUS TO AGRICULTURE

beginning of the year 1892 was crowned with success. Six adult insects and several of the larvæ arrived in living condition at Alexandria. They were set at liberty upon an orange tree infested with Icerya ægyptiaca, and accommodated themselves so well to this new food that in a short time they had become so numerous as to cause an almost complete disappearance of the Icerya. But later the Icerya again began to increase. Happily, however, the Novius had not entirely died out and it also recommenced to multiply, and, thanks to the successive see-saw movements between the two species, the Icerya is held in check in a definite way.

Icerya purchasi and Novius cardinalis in the Hawaiian Islands.—In the Hawaiian Islands, the alarm provoked by the invasion of Icerya purchasi was of short duration. The injurious insect was discovered in 1889 in the suburbs of Honolulu, and multiplied there with rapidity. In 1890, Novius cardinalis was in its turn introduced from California, and a year afterwards the trouble was entirely stopped.

Icerya purchasi and Novius cardinalis in Portugal.—In 1897, the presence of Icerya purchasi was discovered in the orange groves around Lisbon, and the agricultural population began to be alarmed. This insect had multiplied already for several years along the banks of the Tagus River, and it seemed that the first infested plants had been brought from the Azores, where for a long time the Australian scale insect had existed.

In 1897, almost all the gardens of Lisbon and its suburbs were infested with Icerya, and the insect was known to occur in 32 localities. Before attempting the introduction of the natural enemies of the Australian insect, they tried insecticides which were found insufficient to stop the scourge, but which, nevertheless, were of much service from time to time, when it was deemed desirable to introduce Novius cardinalis. Messrs. de Silva and Le Cocq were particularly interested in this latter matter. In spite of a hostile press and the opposition of the greater part of the administrative authorities, they placed themselves in relations with Mr. Howard, the learned director of the Bureau of Entomology, of the Department of Agriculture of the United States, and he wrote to San Francisco, to the State Board of Horticulture of California, and procured from Mr. Alex. Craw sixty Novius cardinalis in the adult condition, as well as a certain number of larvæ in different stages of development.

As soon as they arrived in Washington, in October, these insects were placed in boxes with moss with an ample supply of Iceryas for food, and were then sent on to Lisbon. The greater part of the Novius perished on the voyage. Five only, coming from larvæ which transformed on the journey, arrived alive at their destination. On their arrival they were placed in breeding cages at the Experimental Agricultural Station of Lisbon, and were cared for in such a fortunate way