alternative definition added almost 16 years ago by Andy Deans
A sclerotic ring surrounding the outer spiracular opening.
Reference: Evans, H. E. 1987. Chapter 27 Order Hymenoptera. Pp. 597-710 in: Immature Insects, vol. 1 (F. W. Stehr, ed.). Kendal/Hunt,Dubuque, Iowa. 754 pp.
Cross reference:
None provided.