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Page:Popular Science Monthly Volume 65.djvu/321

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317
THE SAN JOSE SCALE.

peach scale being very widely distributed in those countries and the San Jose scale also in northern China and portions of Japan. In this country, on the other hand, the San Jose scale is practically its only host insect, and in spite of the wide dissemination of the San Jose scale, it still occurs after all in a very scattering way in orchards here and there, with often twenty or thirty miles between places' of infestation. This imported insect can not, therefore, multiply and extend itself as rapidly and naturally as would be the case if the San Jose scale occurred more generally. For this reason it will be necessary to distribute the imported beetle artificially for some time. In Georgia, Alabama and other regions where there are general orchard districts it will undoubtedly be able to take hold much better than it will in regions where orchards are more scattering and of smaller area. Ultimately it is hoped that it will become established in America and have the same beneficial action which it now has in China and Japan. It probably will not be a complete remedy for the San Jose scale for the reasons already indicated, but if it will keep the San Jose scale in check as much as it does in its native country it will be of very decided service. One of its chief advantages will be the fact that it ultimately will take hold of the scale in many small orchards and gardens, the owners of which would be indifferent and would not undertake remedial operations, and thus furnish centers for additional reinfestation.

The importation of this insect can not work anything but good. It feeds only on scale insects, and ultimately may feed on certain of our native species as well as on the San Jose scale. It is a most voracious feeder, and has been observed to eat as many as five or six scale insects a minute, and even an average of but one a minute would give a total of 1,440 scale insects destroyed per day. The appetite of the larva seems never to he satisfied, and it is eating practically all the time. The adults also feed actively on the scale.

The chief drawback to this importation is the fact that several of our native predaceous insects have at once acquired a rather decided liking for the larvæ of, the Chilocorus. A parasitic insect of our native ladybirds has also been attacking it in considerable numbers. These predaceous and parasitic insects may be sufficient to prevent this imported ladybird from giving the benefits which it ought. They have been especially in evidence in the Washington colony, but do not seem to have done any considerable damage in the more southern colonies referred to, and it may he that the ladybird will not suffer materially from them.