Meeting Abstract

50.4  Saturday, Jan. 5  Biomechanics and Visual Ecology of Directed Aerial Descent in Larval Stick Insects ZENG, Y.*; DANIEL, T.; DUDLEY, R.; Univ. of California, Berkeley; Univ. of Washington; Uni. of California, Berkeley dreamoniz@gmail.com

Recent work has shown that many tropical ants falling from trees can direct their paths to return to the tree trunk, but the possible generality of this behavior among arboreal arthropods has not been assessed. Here, we describe how instars of Macleay’s Specter Stick Insect (Extatosoma tiaratum) direct their falls and glide towards vertical columns. We used a combination of video filming and mathematical modeling to quantify glide performance. Preliminary results suggest that there is a significant non-random bias of the descent path, and that the capacity for directed descent is both size- and age-dependent. Prior work with gliding ants has demonstrated visual orientation towards grey tree trunks that are highly reflective relative to the green foliar background. Directed aerial descent in E. tiaratum nymphs is also visually mediated. In a series of behavioral tests, E. tiaratum nymphs tend to direct their glides to high-contrast targets rather than any particular color or brightness. We conclude that gliding behavior in larval E. tiaratum is strongly influenced by the reflectance properties of the target and its surrounding visual environment, and specifically by the contrast between target and background.