Structures of the Lepidopteran abdomen

10 segments with segments 9-10, and often 7 & 8, modified to form the genital structures.
Each typical segment has a sclerotised dorsal plate (tergite) which extends around the lateral walls of the abdomen, and a smaller sclerotised ventral plate (sternite). Paired spiracles (orifices for respiration) are present in the lateral walls (pleura) of tergites 1 to 7.
Paired tympanal organs are present in the first segment in Families Pyralidae, Drepanidae (incorporating Thyatirinae) and Geometridae

For internal genital anatomy see       MALE GENITALIA               FEMALE GENITALIA

The first abdominal segment is modified to facilitate articulation with the metathorax. In primitive families sternite 1 is much reduced and in all Heteroneura it is completely absent; in Ditrysia sternite 2 lies under tergites 1&2.

Acronicta leporina, female, lateral view of metathorax and abdomen with numbered tergites © Chris Lewis

Acronicta leporina, female, ventral view of metathorax and abdomen, heated in KOH and immersed in water, sternites marked. Note that sternite 1 is not identifiable. © Chris Lewis

Acronicta leporina, female, lateral view of metathorax and abdomen, heated in KOH and immersed in water, ovipositor extended, tergites marked. Spiracles visible on segments 2 to 6 but not on 1 or 7. © Chris Lewis

Acronicta leporina, female, close-up ventro-lateral view of segments 7-10, showing external genital structures. © Chris Lewis

Acronicta leporina, female, ventral view, as above, walls of segment 7 removed to reveal ductus bursae © Chris Lewis

Acronicta leporina, female, lateral view distal genital structures, stained with mercurochrome © Chris Lewis