The female lays about 80 eggs, depositing each at the base of a flower head.

In about ten days the larva emerges and burrows into the flower head where it feeds on the developing seeds and florets.

The larva is a small, plump white grub with a dark head and visible body segments.

It overwinters inside the seed head and pupates the following spring.

Nevertheless, knapweed control is better when the moth works in tandem with other insects.