The insecticidal activity and residual effect of two formulations of lambdacyhalothrin were evaluated with
Rhodnius prolixus
;laboratory and field tests were conducted in the State of Chiapas, Mexico. The results indicate that the lethal concentrations of the active ingredient of SC (LC
50 = 2.37 and LC
90 = 8.5 mg, a.i./m
2) were 4-8 times than those with the insecticide WP applied on
R. prolixus bugs in palm leaves, a common building material for thatched roofs. Other investigators in South America recommended applying 30 mg a.i./m
2 in porous materials; we obtained that the products WP and SC were 3.5 and 16 times more effective on palm leaves. Regarding the evaluation of the residual effects in field spraying, there was up to 15 months persistence after the application of WP in two doses (8.6 mg a.i./m
2 and 3.752 mg a.i./m
2) with SC. We consider
R. prolixus highly susceptible to the employed pyrethroids; they could be used to control this vector in the state of Chiapas, Mexico.
