Giant horntail

Giant horntail ©Dr Malcolm Storey

Giant horntail

Scientific name: Urocerus gigas
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.

Species information


Length: up to 4cm

Conservation status


When to see

May to August


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.

How to identify

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.



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.

How people can help

Many of our often-overlooked insects are important pollinators for all kinds of plants, including those which we rely on like fruit trees. The Wildlife Trusts recognise the importance of healthy habitats to support all kinds of species throughout the food chain, so look after many nature reserves for the benefit of wildlife. You can help too: volunteer for your local Wildlife Trust and you could be involved in everything from coppicing to craft-making, stockwatching to surveying.