Method of Obtaining an Index to Density of Field Populations of Citrus Red Mite

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Abstract
This method involves the random collection of 50 leaves from each of the 2 sides of a citrus tree, and when present, the selection of 3 heavily infested fruits from 3 relatively constant locations. Each sample is placed in 800 cc. of 5% formalin immediately after picking and brought into the laboratory where the eggs are removed from the leaves by a 5 min. immersion in 800 cc. of 0.25% hot KOH. The 2 solns. containing the mites and eggs are combined in a Dazey churn operated by an electric motor and geared to turn at 150 r.p.m. Agitation at this speed is sufficient to insure an adequately uniform distribution of mites and eggs throughout the suspension. During agitation a 200 cc. aliquot is removed and filtered in a Beuchner funnel through filter paper stamped with parallel guide lines of indelible ink. The mites and eggs thus secured are counted under a low power binocular microscope; they represent 1/8 of the total number of mites and eggs present in the sample. 50 leaves from each of the 2 sides of a tree with or without the inclusion of the 3 fruits were found to be a significant sample of the total population on a tree.

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