Structural variation in the pterostigma of percher and flyer dragonflies (Odonata: Anisoptera)

Insect wings possess morphological adaptations that have been selected for efficient flight aerodynamics. In odonates, the pterostigma is a structure located toward the distal leading edge of the wing. While the pterostigma is relatively understudied regarding its role in dragonfly flight dynamics, it is hypothesized to contribute mass toward the leading edge of the wing to provide stability, increase critical flying speed, and reduce the possibility of wing damage during prolonged and high-speed flight. Dragonflies can be categorized into 2 broad types of flight behavior: perchers, which spend most of their time perched on vegetation, and flyers, which spend much of their time in flight. Because perchers and flyers vary in flight demands, we hypothesized that there may be differences in the structural characteristics of the pterostigma that correlate with the 2 flight modes. To assess morphological differences of the pterostigma between perchers and flyers, we measured surface area, length, and mass characteristics of the fore- and hindwing pterostigma. We found that perchers had larger and heavier fore- and hindwing pterostigma than flyers, despite having lighter bodies and wings. We suggest that a larger pterostigma in perchers may be associated with the need for greater wing torque during rapid, maneuverable flight.