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32

experiment III, both chlordane and heptachlor gave equally poor results by producing less than lS per cent kill. These results are presented in figure 21.

Response of nymphs and adults to chemicals

A comparison of experiments II and III where environmental conditions (temperature and relative humidity) were essentially the same, reveals a noticeable difference in the rapidity and degree of kill obtained between adults and nymphs. In every instance, the adults showed a much longer initial moribundity reaction to the chemicals followed by a decidedly poorer kill.

Comparison of the light, medium and heavy concentrations

A comparison is shown in figures 22 to 29 of the rapidity and degree of effectiveness with which the three concentrations of each chemical reacted against earwigs for the first series of experiments II and I II only. The differences between the light, medium and heavy concentrations in experiment I were so slight that graphical comparison seemed rather purposeless.

As was previously indicated, and as is readily seen in these graphs, the most notable difference between experiments II and I II is the per cent effectiveness achieved per given period of time. In the former, where fourth instar nymphs and adults were used in equal proportions, the rapidity and effectiveness of all chemicals exceeded that of the latter where only adults were used.

There is a strong correlation between the concentration of a chemical and its effectiveness. It will be noted in looking at the figures, that in all cases, the heavy dosage exceeded the medium and light ones in giving the highest per cent of kill. In experiment II (figures 22)