Elastocapillary effect in self-repair of proboscises of butterflies and moths.

Hypothesis: Self-repair in living organisms, without tissue regeneration or regrowth, is rare. Recent discovery that butterflies can self-repair the proboscis after the two halves (galeae) have been separated raised a question about the physical mechanism allowing them to reunite the parts. We discovered that butterflies pump saliva during repair of their proboscises.

Self-assembly of the butterfly proboscis: the role of capillary forces.

The proboscis of butterflies and moths consists of two C-shaped fibres, the galeae, which are united after the insect emerges from the pupa. We observed that proboscis self-assembly is facilitated by discharge of saliva. In contrast with vertebrate saliva, butterfly saliva is not slimy and is an almost inviscid, water-like fluid.