The common emerald (Hemithea aestivaria) is a moth of the family Geometridae.

The species is found throughout the Nearctic and Palearctic regions and the Near East.

It is mostly commonly found in the southern half of the Ireland and Britain.

The hindwings have a sharply angled termen giving the moth a very distinctive shape.

[3] It flies at dusk and night in June and July[4] and will come to light.