Aeshna isoceles (or isosceles) is a small hawker dragonfly that is found in Europe, mostly around the Mediterranean, and the lowlands of North Africa.

Aeshna isoceles is brown, with green eyes, clear wings, and a yellow triangular mark on the second abdominal segment which gave rise to its scientific name.

Both have a brown thorax and abdomen but A. isoceles has green eyes and clear wings and a diagnostic yellow triangular mark on the second abdominal segment.

It is now confined to relatively unpolluted fens and grazing marshes in the Broadlands of Norfolk and north-east Suffolk.

Since 2011 the species has also been recorded in the Stour valley in east Kent[3] where egg laying has been observed and it appears to be spreading.

It is protected under Schedule 5 of the Wildlife and Countryside Act 1981[4] and listed in Category 1 (endangered) in the British Red Data Books on Insects.