The morphology of antennae sensilla and sex pheromone gland of Maruca testulalis Geyer were observed under scanning electron microscope. Antennae were made up of scapus, pedicle and flagella. The latter consisted of 72-82 segments and was about 86-97 cm long. The upper surface of antennae was covered with cataphylla and most of the antennal sensilla lied on its side and lower surfaces. Six kinds of antennal sensilla were found in both sexes. Sensilla cylindric were observed on male antennae and an undefined sensilla was observed on female antennae only. Sensilla trichodeum of males were longer than that of females. The number of sensillum trichodeum was lesser on females antennae than males antennae. The study showed the sex pheromone gland was situated in the intersegmental membrane between the eighth and ninth abdominal segments, which was verified by GC-MS analysis.