Butterflies and Moths

40

Silk cocoons

Moths, like butterflies, spend the third stage of their

life cycle as a pupa. Many moth caterpillars spin a

cocoon to protect them while they pupate. Silkworms—

which are not really worms at all, but the caterpillars

of the silkmoth—spin a very fine silken thread to make

their cocoons with. We use this thread to weave

delicate clothes.

Cosy corner

The silkworm chooses

a safe, cosy place to

spin its cocoon. This

can take two days, and

the silken thread can

be 2,600 ft (800 m) long

by the time the cocoon

is finished.

The silkworm begins to spin a

silken thread that comes out

through holes under its head.

As the silkworm

continues to spin

silk, the cocoon

gets thicker.

The cocoon is now

strong enough to

protect the silkworm

as it changes into a pupa.

US_040-041_Silk_cocoons.indd 40 11/10/17 3:34 pm