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46 Results of field treatments with granules Results from the application of granular
insecticides to a series of experimental field plots, in which a heavy earwig infestation had existed, are given as total
active numbers in table 5 and in per cent control based on the check plots in figure 40. In rapidity and degree of
effectiveness, heptachlor and dieldrin were parallel as were aldrin and
chlordane (figure 40). Heptachlor and
dieldrin were more rapid to take effect, giving a 98 and 95 per cent control, respectively,
on the fifth day. Aldrin and
chlordane after the same period had effected on a 73 and 66 per cent control,
respectively. All four chemicals tended to converge with respect to their
degree of effectiveness on the sixth day and were thereafter essentially
indistinguishable. On the 28th day when the last
counts were made, all chemicals have converged within a narrow margin of
96-99 per cent control. A glance at
table 5 will show the small number of
earwigs caught at this time in the treated plots. |