Scientific Name: Eurygaster spp (Scutelleridae).
English Name: Tortoise bugs (Jewel Bug family).
French Name: Les punaises des céréales (='a cereals bug'). Also les punaises-tortue (='a tortoise bug').
5 Key Characters:
- all species very variable in colour -- can be yellowish, brown, grey or black, and may or may not have brown stripes.
- may have a central keel down scutellum and pronotum (middle body plate).
- scutellum (large 'plate' on the back) is U-shaped.
- the 'shoulders' are rounded (some species a bit more than others) and extend to the corium (upper outer part of the wing) or just beyond, depending on species.
- quite large for a shield bug, at a bit more than a centimetre long.
Lookalikes: There are 5 species of Eurygaster in France, and all are extremely difficult to tell apart. E. austriaca, E. testudinaria and E. maura are the most common. The differences are subtle and difficult to judge without having all the species in the hand to compare, or good dorsal photos (looking straight down on the insect). E. austriaca has the most pronounced keel, others may have none at all. Another key character is the relationship of the clypeus (the central front part of the head) with the 'cheeks'.
Habitat: Cereal crops, hot dry calcareous wild flower rich grassland. E. testudinaria prefers damper habitat.
Adult Active Period: All year, but especially May to August.
Status: Three species are widespread and quite common, can sometimes be a pest of cereal crops.
Further Reading: Note that Insects of Britain and Western Europe by Michael Chinery is not much use for Eurygaster in France. It only shows the two British species and the characters listed for them are not reliable for separating these two, much less from any of the others. The best resource is the online forum Le Monde des Insectes (in French).
Photographed by Loire Valley Nature: