Wing colours may also attract a mate. The wings of many male lepidopterans have scent glands to attract females as well. Silk More than 2000 years ago, the Chinese discovered that certain caterpillars make a fine, light thread that can be woven into one of the most beautiful of all materials, silk. Most moth caterpillars make silk. It oozes as a fluid from glands beneath their mouth, then hardens into a thread.
Caterpillars use the thread to spin the cocoons in which they change into an adult moth.
With most cater-pillars, the cocoon is made from short lengths of thread glued together, but the mulberry silkworm caterpillar makes its cocoon from a single thread up to 1km long. This thread can be retrieved only by softening the cocoon in hot water, killing the pupa. Silkworms are extinct in the wild, but are reared on special farms where the mulberry trees on which they live have been planted. They are usually laid on plants that provide food after hatching. Larva Caterpillars are hungry eaters, chewing their way rapidly through leaves.