The halteres on the metathorax are the morphological equivalent of the metathoracic wings. The eighth and last segment of the female contains the anus and no spiracles. In the female, the vulva lies between the apices of the gonopods. These irregular tubes extend into the body from the surface. Two gonopods terminate internally and are known as spermatheca.
Males have a genital opening between their ninth and tenth abdominal segments.
The spiracle of the seventh segment has been moved forward to a more anterior position in the segment. The ninth segment is highly modified and bears a large dorsal plate that extends to become a narrow band running beneath the anus. The tenth segment is a pair of sclerotized plates flanking the anus. The dorsal ventral patterning of the thorax is regulated by the dorsal-ventral polarity system and segmentational patterning regulated by gap , pair rule and segment polarity genes. The two transcripts of Antennapedia take on different roles in ectoderm and endoderm and in the three thoracic segments.