Abstract:
Two formulations of DDT and one of BHC were tested against the cattle tick (Boophilus microplus Canest.). The DDT preparations, a dispersible powder and a dispersible paste, were not as toxic to the tick as the colloidal formulation reported on by Hitchcock and Mackerras (1947). The BHC preparation at a concentration of 0.05 per cent. gamma isomer killed almost all ticks but the period of protection against reinfestation was shorter than that afforded by this colloidal DDT preparation. The results of analyses are presented to illustrate the concentrations maintained during dippings and the rates of dispersion and settling.