Length 9 to 11 mm. A fairly large shieldbug, the two Eurygaster species are often known as Tortoise Bugs. The ground colour and intensity of the markings are variable, including dark purplish- or reddish-browns with cream striping.  In adult Eurygaster testudinaria, the second antennal segment is less than twice as long as the third segment.  This is difficult to confirm from a photograph, and in order to verfiy as a species, genital examination is necessary.  

Eurygaster maura is very similar and can only be reliably separated from E. testudinaria by genital examination. 

genitalia

Determination of this species requires genital examination.  For females, also provide a close-up photograph of the external gentialia underneath the tip of the abdomen; for males, provide a photograph of dissected aedeagus.

Dry and damp grasslands.

Adult: All year.

Nymphs feed on grasses between May and August, becoming adult from June.

Previously uncommon, it is now widespread in southern Britain and Ireland in and is expanding its range northwards.

Frequent

https://www.britishbugs.org.uk/heteroptera/Scutellerideae/e_testudinaria.html