Giant horntail

With yellow-and-black bands, the giant horntail looks like a large wasp, but is harmless to us. The female uses her long, stinger-like ovipositor to lay eggs in pine trees, where the larvae then develop.

Top facts

Stats

Length: up to 4cm

Conservation status

Common.

When to see

May to August

About

The giant horntail is a massive sawfly that is also known as the 'giant woodwasp' or 'greater horntail wasp'. A relative of the wasps, the female is black and yellow and has a long, stinger-like tail that is actually her ovipositor, which she uses to lay her eggs into wood, particularly pine. The larvae live in the wood of pine trees, where they spend up to five years developing. Found near pine woods, or places where pine timbers are used.

What to look for

The giant horntail is a black-and-yellow-banded insect that looks like a large wasp, so may be confused with the hornet or hornet robberfly. The female has a long ovipositor at the end of her body, which looks like a stinger.

Where to find

Widespread.

Did you know?

Despite its fearsome appearance, the giant horntail is harmless. However, the length of time the larvae spend in wood does result in the adults sometimes emerging from harvested timber used for building or even furniture.