alternative definition added almost 3 years ago by Istvan Miko
A rigid tubular structure with sharply defined edges, usually yellow, brown or even black, but sometimes milky or clear; the edges appear darker, the center paler.
Reference: Mason, W. R. M. 1986. Standard drawing conventions and definitions for venational and other features of wings of Hymenoptera. Proceedings of the Entomological Society of Washington 88:1-7.
Cross reference:
None provided.