Bulletin of the of Agriculture . r example, as inthe San Joaquin Valley, where a climatefavorable to the development of the pestand extensive recent plantings of citrusoffer an ideal environment. In southernCalifornia it becomes seriously injuriousonly in certain seasons and only in thelocal sections about Riverside, Red-Highland, and Rialto, in-jury decreasing as the coast isapproached. The natural hab-itat of the citrus thrips, there-fore, appears to be thearid Lower Sonoran lifezone of North Amer-ica. This belief issubstantiated fur-ther by its oc-currence onplants na-tive to
Bulletin of the of Agriculture . r example, as inthe San Joaquin Valley, where a climatefavorable to the development of the pestand extensive recent plantings of citrusoffer an ideal environment. In southernCalifornia it becomes seriously injuriousonly in certain seasons and only in thelocal sections about Riverside, Red-Highland, and Rialto, in-jury decreasing as the coast isapproached. The natural hab-itat of the citrus thrips, there-fore, appears to be thearid Lower Sonoran lifezone of North Amer-ica. This belief issubstantiated fur-ther by its oc-currence onplants na-tive to thisregion anddistant fromcitrus citrusthrips isknown to oc-cur in eight counties in California (see fig. 1), viz., Sacramento,Fresno, Tulare, Kern, Los Angeles, San Bernardino, Riverside,and Orange. The infestation is most serious in Tulare, Fresno,Riverside, and San Bernardino Counties. In Kern County theinsect is increasing rapidly and with increased plantings of citrusdoubtless will become quite as injurious as in Tulare Fig. 1.—Map showing present known distribution of the citrus thrips(Scirtothrips citri) in California. (Original.) THE CITRUS THRIPS. 3 Although the insect occurs in injurious numbers in Arizona, thus farit has been taken only in the Salt River Valley near Phoenix andMesa (fig. 2). Dr. A. W. Morrill informed the writer by letter thathe thought he detected traces of thrips injury in an orange grove nearYuma,_but specimens have not been taken there. POSSIBILITY OF ITS OCCURRENCE ELSEWHERE. No verified reports of the occurrence of the citrus thrips in Statesor countries other than the foregoing have been made, although itis said to occur at Hermosillo, Sonora, Mexico. There are variousreports of thrips injuring citrusfruits, the species concerned beingoften in doubt. Thus, Towerxstates that certain scars found onoranges in Porto Rico probablyare caused by thrips which werepresent in the trees in great num-bers, but the identity of the thri
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
