Abstract Anopheles triannulatus bachmanni biting man were collected at Aripuana, Mato Grosso.In paired catches L-TRYPTOPHAN less than 5% of the insects were collected biting inside houses, most insects were collected at the edge of the rain forest at sunset.Physiological age determination indicated an even age distribution Organic Dish in the females but the insects flight behaviour would make it of little importance as a vector of malaria.