The human blood index (HBI) of the three malaria vectors collected from different habitats at households with and without livestock in the Kilombero Valley. Data pooled over all years of study (2007–09). Black bars are for HBI inside houses, grey for outdoor resting box, and white for cattle sheds. Error bars represent one standard error. Note: **indicates there were no blood-fed An. funestus collected inside houses at households with livestock.