sentence: Silk starts out as a liquid in the salivary glands.
sentences_before: All caterpillars can make silk. The silk is made from the salivary glands.
sentences_after: The caterpillar draws out the silk into a small thread. The silk hardens as soon as it is exposed to the air. Caterpillars use silk to make nests or cocoons.
concept_name: silk
headings: Butterfly Life cycle Caterpillar