A male Emperor moth can smell a female from 6 miles (9.6 KM) away.
According to the results of German experiments carried out in 1961, the male emperor moth (Eudia pavonia) can detect the sex attractant of the virgin female at a range of 11 km (6.8 miles). This scent has been identified as one of the higher alcohols (C16H29OH), of which the female carries less than 0.0001 mg. The chemoreceptors on the male moth’s antennae are so sensitive that they can detect a single molecule of scent.