Elm-leaf beetle

Xanthogaleruca luteola, commonly known as the elm-leaf beetle, is a beetle belonging to the family Chrysomelidae.
The imago is 6–8 mm in length, ranges from yellow to green in colour, with a spot on its head, an hourglass mark and two spots on the pronotum, and a broad, dark stripe along the edge of each elytron. The larvae are usually black, occasionally black and yellow, with multiple rows of dots on the back and on the sides and < 13 mm long. The pupae are orange-yellow with black chaetae. The ova are yellow, and laid in spindle-like clusters of < 25 on the undersides of the elm leaves.
These beetles are common in the Western Palaearctic ecozone from Portugal to Central Asia. Indigenous to Europe, it was accidentally introduced to North America and Australia (wiki)
This particular beetle, was spotted in central Volos city, Greece, as in Kassaveti street there are some pretty huge and quite old Ulmus procera trees.