Meeting Abstract
P1.195 Friday, Jan. 4 Flexural Stiffness & False Head Behavior in Lycaenidae Hind Wings VOLZ, L/J*; TAYLOR, E/M; SIMPSON, K/B; FIELD, B/S; MCCLOUD, E/S; DAVIS, J/L; University of Southern Indiana; University of Southern Indiana; University of Southern Indiana; University of Southern Indiana; University of Southern Indiana; University of Southern Indiana jldavis2@usi.edu
Insect wing mechanics have been studied with the motivation of characterizing the relationship between flight and mechanical properties, including flexural stiffness. Lyceanid butterflies offer a different mechanism for which flexural stiffness may contribute to behavior. Lycaenidae have characteristics of their hind wings that are described as a false head; including posteriorly oriented wing projections called tails. While maneuvering on a substrate many Lycaenidae fold and oscillate their hind wings along the cephalic-caudal axis. At this time, the tails oscillate in a peculiar bouncing motion. This is called false head behavior. One of the predictions from the “False Head” hypothesis posits that false head behavior deflects predator attacks away from the vulnerable body and head toward a weaker decoy region of the insect that can break away upon attack similar to the autotomizing tails of lizards. We predict that this weaker region in the hind wing may be a result of decreased modulus. We measured flexural stiffness profiles of butterfly wings along the length of the wing. We used these measurements along with finite element models to predict average modulus of the wing. Uniform moduli of wing membrane and wing vein structures can predict the flexural stiffness to within approximately 18% of mechanically tested wings. However, preliminary results indicate regional variation of wing moduli allows us to better capture the flexural stiffness profile observed in experimental data. In addition, dynamic analysis of the wing models indicate that there may be a mechanical relationship between hind wing movement and tail bouncing.
