Length 5 to 7 mm. Mainly orange with just the dorsal surface of the thorax black. Legs with black rings as with most Athalia species.

Very similar to Athalia cornubiae and females can only be separated by microscopic examination of the hypopygium. Males cannot be separated.

Various habitats.

Summer and early autumn.

The larvae are found on crucifers such as Hairy Bitter-cress and Hedge Mustard.

Widespread and seemingly uncommon, but almost certainly under recorded in Britain.

Rare or under recorded in Leicestershire and Rutland.

https://www.sawflies.org.uk/athalia-liberta/