Study Notes on Wing Venation and Lignination in Entomology

Lignination Overview

  • Lignination is a term discussed in the context of the worksheets provided for understanding wing venation in entomology.

  • Two worksheets given:

    • One for practical work on wing venation.

    • Another as a guide, originally drawn by an early entomology teacher of the lecturer.

Wing Structure and Terminology

  • Focus is primarily on the forewing due to complexity:

    • Understanding venation in the forewing is pivotal as it has most of the intricate details compared to the hind wing.

Wing Margin Areas

  • Various references to specific areas of the wing are included:

    • Anal Margin

    • Costal Margin

    • These terms provide a framework for understanding the wing's structure.

Historical Context of Wing Venation Nomenclature

  • The diagram's wing venation follows the nomenclature established by Needham and Comstock:

    • Noted entomologists in the 1800s in the U.S.

    • Comstock had associations with Cornell University.

  • Their system categorizes wing veins into two main types:

    • Longitudinal veins: Run from the body outward along the length of the wing.

    • Cross veins: Horizontal veins intersecting the longitudinal veins.

Naming Convention for Wing Veins

  • Veins are counted from the top of the wing downwards:

    • Costa: The first and topmost vein across the wing.

    • Subcostal Veins (SC): Named subcostal 1 (SC1), SC2, etc., moving from the inside of the body to the outer margin.

    • Radius Veins (R): The main radial vein begins at the base and branches:

    • First branch is R1, followed by radial sector (RS) before continuing to R2, R3, etc.

    • Medial Vein (M): Begins at the base and branches accordingly down the length of the wing.

    • Cubital Vein (C): Follows the medial vein in the vein hierarchy.

    • Anal Vein (A): All branches stemming from the cubitus are collectively termed as anal veins (An, A1, A2, A3), also capable of being represented by Roman numerals. This nomenclature includes a count from top to bottom despite the physical proximity to the body.

Branching and Complexities in Wing Venation

  • Some complexities occur in flies:

    • If a vein branches and later rejoins, it can be labeled as R3 and R4, emphasizing the necessity of tracing vein patterns throughout the wing.

  • Discussion of learning curve frustrations surrounding wing venation:

    • The lecturer expresses personal difficulties with the nuances of studying insect wing structures.

Crossings in Wing Veins

  • While some vein crossings are not labeled in the presentation, an external resource from NC State Entomology site will further illustrate them:

    • Humeral Vein (H)

    • Sector Vein: Medial branch connections.

    • Vein Naming Conventions:

    • Horizontal veins are labeled with uppercase letters, while vertical veins take lowercase letters.

    • Example: MCU denotes a branching between medial vein (M) and cubital vein (C).

Class Activity and Collaboration

  • The class will focus on collaboratively working through the provided worksheet to practice and apply knowledge:

    • Initial focus on the first image, followed by additional diagrams in subsequent figures.

    • Students will be tasked with labeling three unknowns on the back of the worksheet.

    • An answer key is available but should not be consulted before attempting the worksheet to foster independent learning.

    • Encouragement provided for teamwork: "It’s more fun to suffer collectively than by yourself."

Questions and Interaction

  • The lecturer invites questions throughout the discussion, recognizing possible confusion but promotes group engagement for clarification.