Background:It is environmental to use botanical insecticides to control red imported fire (RIFA), Solenopsisinvicta.TheDerris trifoliateroots powder were evaluated for its efficacy in the control of S.invicta under both laboratory and field conditions.Results: The D.trifoliate roots powderexhibited strong toxicityagainst macroergate and micrergate of RIFA, especially when we used 120 mesh sieve to collect D.trifoliate roots powder.Rotenone content in D.trifoliate roots powder, which was collected by 120 mesh sieve, was the highest than D.trifoliate roots powder collected by 100 mesh sieve, 60 mesh sieve and blank.D.trifoliate roots powder collected by 120 mesh sieve also showed that it had the lowest LC50 (1.99 mg/kg and 1.69 mg/kg) and KT50 (22.04 h and 14.08 h) against macroergate and micrergate of RIFA than D.trifoliate roots powder and other powder collected by 100 mesh sieve,60 mesh sieve and blank.Under field conditions,thepowder-sand,formulated with the D.trifoliate roots powder which was collected by 120 mesh sieve, had the significant effect on RIFA thanpowder-sand whose powder was collected 100 and 60 mesh sieve and blank-sand when treated after 30d.Conclusion:The D.trifoliate roots powder, which was collected by mesh sieve, was showed higer efficience than without any deal to control S.invicta under both laboratory and field conditions and it can be used as an effective agent against RIFA.The tinier trifoliate roots powder was, the high control efficiency.