A butterfly is able to drink nectar from a proboscis. It stays tightly coiled up when not in use. When it feeds, it stretches it out, and probes down into the flower to feed. When a butterfly first emerges (ecloses) from its' chrysalis, the proboscis is in 2 parts. They need to uncoil and coil it up a few times to 'zip' the 2 halves (galea) up. Each side is a trachea that helps them breathe. When the 2 halves are zipped together, a central feeding tube is formed. You can see the 2 halves in these pics.
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