. Airplane dusting in the control of malaria mosquitoes. Mosquitoes Control. 4 Department Circular 367, U. S. Dept. of Agriculture tion of the wind and to two lines of glass plates placed at intervals across an open field. In the best of the trials it was found that a strip from 300 to 400 feet wide had been effectively treated by one trip of the plane and that the quantity of Paris green required was at the rate of about 1 pound to 20 acres. This represented the minimum quantity effective on water containing almost no debris or aquatic growth. Under such conditions the writers' counts had sho
. Airplane dusting in the control of malaria mosquitoes. Mosquitoes Control. 4 Department Circular 367, U. S. Dept. of Agriculture tion of the wind and to two lines of glass plates placed at intervals across an open field. In the best of the trials it was found that a strip from 300 to 400 feet wide had been effectively treated by one trip of the plane and that the quantity of Paris green required was at the rate of about 1 pound to 20 acres. This represented the minimum quantity effective on water containing almost no debris or aquatic growth. Under such conditions the writers' counts had shown that 10 or more granules of Paris green per square inch usu- ally gave 100 per cent mortality, whereas with a lower count some of the larvse escaped. In these preliminary tests and in the next series also a count of 10 granules per square inch was therefore taken as the effective dosage, although it was found later that this quantity was insufficient under natural breeding conditions where the larvse. Fig. 2.—Dust cloud beginning to spread out among the trees following a trip of plane across Bunkum Woods are more protected by the debris and vegetation among which they feed. The next tests were made in two patches of woods, to deter- mine whether the dust could be forced to the ground through a growth of leaves and brush. In the first of these the strip of woods was fairly narrow, with only a moderately heavy growth of timber. Two parallel lines of glass plates were placed on the ground under the trees and the plane was flown at right angles to these lines, mak- ing two or three trips across the woods at about the same place each time (fig. 2). The mixture distributed consisted usually of 100 pounds of dust containing 10 pounds of Paris green. The lines of glass plates, with 10 in each, were distributed across a strip 750 feet wide. In the best one of the trials all of the plates showed the pres- ence of Paris green, and all except two in one line had 10 or more granul
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