Willow redgall sawfly

Its red gall is up to about 1 centimetre long. At first it is green and then turns red.

One willow leaf can have several of these little bean-shaped galls.

Sometimes a tiny weevil or fruit fly sneaks its own egg into the gall and takes over the home.

In New Zealand nobody has ever found a male. The females can have babies all by themselves.

When the larva leaves its gall, it spins a golden-brown cocoon covered with bits of soil and leaves.