Extracts of an annual herbaceous plant, Kochia scoparia (L.) Schrad (Macrophomina), were bioassayed to determine their acaricidal activities against Tetranychus urticae Koch, Tetranychus cinnabarinus (Boisduval), and Tetranychus viennensis Zacher (Acari: Tetranychidae) in the laboratory. Extracts had both contact and systemic toxicity to these mites. Three solvents were tested for preparing crude extracts: petroleum ether, chloroform, and methanol. Methanol was the most effective solvent, extracting 3.11–4.53% of the acaricide. Petroleum ether was the least effective solvent, extracting 1.25–1.54%. However, extracts with chloroform resulted in the highest mite mortality (78.86%), and ultrasound-assisted extraction required the least time (10 min). Concentrated extracts were prepared using chloroform, methyl acetate, or distilled water as a solvent. Mite mortalities from the concentrated extracts by methyl acetate or distilled water were significantly lower than those by chloroform. The mean lethal concentrations (LC₅₀) of the extracts by chloroform, methyl acetate, and distilled water to the mites were 0.71 ± 0.06, 2.08 ± 0.16 and 8.75 ± 0.062 mg/ml, respectively. After liquid chromatography and thin layer chromatography, the concentrated extracts by chloroform were separated into seven groups of isolated fractions and tested for acaricidal activity.