Abstract The procedure is as follows: Hair on guinea pigs is clipped around the midsection. Then 2 capsule cages each containing 12 starved nymphal lone star ticks are attached with contact cement and tape to each animal. Those guinea pigs receiving the candidate compound are treated 24 h later. An untreated pig serves as the control and provides data for Abbott’s formula. Doses of the active ingredient depend on guinea pig weight, compound structure, LD50, and other considerations though the maximum is 30 mg/kg. This amount Is formulated in diethyl succinate and administered subcutaneously on 3 alternate days, a volume of^500 ul/injection. About 4-6 days after the 1st treatment, dead ticks in the cages are detached and counted, and/or replete ticks were removed from the capsules and held to observe mortality and nymphal molt. Effectiveness is determined by the percentage of ticks that fail to ecdyse (including dead nymphs that detach without engorging).