Meeting Abstract
We have investigated and are exhibiting a methodology for studying the self-repair mechanism of the split lepidopteran proboscis in active and sedated butterflies. To probe the repair capabilities, we have separated the proboscis far from the head with a metal post of diameter comparable to the butterfly galea and moved the post ever closer to the head in increments of 500 microns until the proboscis was fully split. Once split, we brought the post back towards the tip in steps and observed the convergence of the two galeae back into one whole proboscis. To determine the materials properties of the proboscis, the process of galeae gathering was filmed with a high speed camera. The galea profile, extracted from the videos as a function of time, was then fitted with a mathematical model based on the Euler-Bernoulli beam theory where each galea was treated as a beam undergoing small deflections. The theory was augmented by introducing the bending moments modeling the muscular action as well as by a capillary force due to the saliva meniscus. Experiments on sedated butterflies, when the muscular action was diminished but saliva was present, show the crucial role of saliva meniscus in bringing galeae together. The model sheds light on the evolutionary development of the butterfly proboscis; in particular, the effect of the galea cross-section and anisotropy of materials properties.
