The sprays containing pyrethrum were outstanding in their high toxicity to the tick, and should be used where spraying measures are employed until a substance is discovered of the same order of toxicity.

Of the dusts, pyrethrum powder was again, outstanding in its activity. If it is to be used, tests should be done beforehand to make certain that the sample is a good one.

Other dusts were tested because pyrethrum powder is likely to deteriorate rather rapidly in the field. Certain derivatives of phenol and naphthalene were active as fumigants. Although these substances would evaporate quickly in contact with the general atmosphere, they might have some use as soil-fumigants in the floors of huts. Other derivatives acted purely as contact poisons and yet were just too volatile to be lasting in the general atmosphere. Alpha-naphthylamine and 3-methyl.6-ethyl.phenol are examples. Of these two, the latter is more toxic, and it is possible that the substitution of a higher alcohol for the methyl or ethyl group would decrease the volatility but not the toxicity.